Web directory, archive
Search web-archive-uk.com:

Find domain in archive system:
web-archive-uk.com » UK » C » CHAM.CO.UK

Total: 682

Choose link from "Titles, links and description words view":

Or switch to "Titles and links view".
  • CELL and CELL-FACE characteristics
    The area porosity Just as VPOR represents the free volume fraction so EPOR NPOR and HPOR represent the free fractions of the East North and High cell face areas Here free signifies effective for convection and diffusion 3 2 In terms of what lies on either side Whether or not the free area fractions differ from their default namely unity convection and diffusion across the faces are influenced by whether the cells on both sides are occupied by fluid in which case both convection and diffusion may take place or at least one of the cells is occupied by solid in which case only diffusion can take place moreover if the face adjoins a cell for which PRPS equals VACPRP no diffusion can occur or if it adjoins a cell for which PRPS equals PORPRP only momentum diffusion can occur while if a fluid cell adjoins a solid cell having any other PRPS value diffusion can occur only for momentum and for heat transfer the cell face lies on the north high or low boundary of the domain or or on the east or west boundary of the domain with XCYCLE false in which case neither diffusion nor convection can occur 4 Logical functions for determining cell or cell face character Programmers wishing to characterise a cell can thus do so by inspecting its PRPS value and If they wish to characterise a cell face in respect of convection or diffusion they can therefore do so by asking is it on a boundary and or what are the PRPS values of the cells on each side However in order to assist them to do so and to embody the answers to the questions in their Fortran coding PHOENICS provides two sets of logical functions The first set comprises slab wise oriented functions which use the cell address designated as IJ below relative to the current slab The second set includes whole field logical functions which need the absolute cell address designated as IJK below There are functions of two different types in each set volume related functions which return status of a cell and face related functions which return status of a cell face First consider the slab wise oriented logical functions There are three volume related functions SLD IJ returns TRUE if the cell is occupied by a solid POR IJ returns TRUE if PRPS for a cell is equal to PORPRP and VAC IJ returns TRUE if PRPS for a cell is equal to VACPRP The face related functions form several groups Each group comprises six functions one function for each cell face The available groups and functions are listed below Functions to test for a presence of phase boundary at the cell face are NF IJ returns TRUE if north face of a cell is phase boundary SF IJ returns TRUE if south face of a cell is phase boundary EF IJ returns TRUE if east face of a cell is phase boundary WF IJ returns TRUE

    Original URL path: http://www.cham.co.uk/phoenics/d_polis/d_enc/cellstat.htm (2016-02-15)
    Open archived version from archive

    signify that for the whole domain of simulation the first phase material has the properties associated with material 0 of the PROPS file while the second phase material has the properties of material 67 It should be remarked the since version 3 4 2 Earth no longer makes specific use of the domain fluid concept but picks up all the information which it needs from other EARDAT items b If the newer In Form based selection by name method is employed the following lines could be placed in the Q1 file in order to select for example mercury as the phase 1 fluid fluid name mercury load 089 Then the Q1EAR EARDAT and RESULT files would all contain copies of the formulae which EARTH will use for the computation of density specific heat viscosity and thermal conductivity The EARDAT version is PROPERTY RHO1 C POL3 TEM1 14 293 2 68226 5 3957 PROPERTY RHO1 CE 4 3 16674E 7 PROPERTY ENUL C POL3 TEM1 5 47854 02372 4 3529 PROPERTY ENUL C9E 5 2 79475E 8 10110 PROPERTY CP1 C POL3 TEM1 159 54 10108 1 23163 PROPERTY CP1 CE 4 3 60116E 8 STORED COND C POL3 TEM1 3 90003 01799 8 2070 STORED COND C1E 6 1 52734E 9 PROPERTY PRNDTL TEM1 C COND 10110 Here the POL3 and TEM1 are clues indicating that third order polynomials are to be used for each of RHO1 ENUL CP1 and COND these being the formulae which are to be found in the loaded input library case 089 In Form s case 089 refers only to phase 1 fluids The just described lines will therefore dictate that mercury is the first phase fluid Of course it can easily be modified to allow phase 2 fluids to be selected Input Library cases which illustrate this mode of property setting are 761 and 762 c The phrase one material fills the whole domain does not it should be mentioned preclude the presence of blocked off regions which the material does not occupy provided that whatever is contained in those regions is without influence on the phenomena being simulated other than perhaps to impose the no slip condition at their boundaries Such regions are indicated by possession of PRPS values see below equal to VACPRP set in the PROPS file for totally non participating volumes or PORPRP also set in the PROPS file for volumes of which the sole influence is to impose the no slip condition at their boundaries 2 2 When different parts of the domain are occupied by different materials It frequently occurs that PHOENICS is required to simulate flow and heat transfer in circumstances in which solid bodies are present Often these solids interact thermally with the fluids Moreover different parts of the domain may be occupied by different fluids as when a glass bottle containing hot water is cooled by contact with external air This requirement is met by assigning different IMAT values to the spaces which each material

    Original URL path: http://www.cham.co.uk/phoenics/d_polis/d_enc/enc_prop.htm (2016-02-15)
    Open archived version from archive

  • The PROPS file
    table can be seen by clicking here Evidently the table is arranged in row and column manner with seven columns the first being for the material index IMAT and the remainder for the 6 allowable properties for each material at least two rows of which one contains its name and another with the IMAT value on the left contains either real numbers or GRNDx further rows containing real numbers below any rows containing GRNDx and possibly other lines which are treated as comments because they contain blanks in the first two columns The arrangement is gases at the top IMAT from 0 to 39 then anonymous fluids IMAT from 40 to 50 liquids in the middle IMAT from 51 to 99 solids at the bottom IMAT from 100 to 197 two fictitious materials IMAT PORPRP and VACPRP SOLPRP PORPRP and VACPRP In order to guide EARTH in its use of PROPS file information the above arrangement is reflected by the setting of the above three variables in the first three active lines of the file SOLPRP usually 100 which indicates the lowest IMAT which represents a solid Fluids are always ascribed lower than SOLPRP values PORPRP usually 198 which is the IMAT assigned to a fictitious solid which influences the flow process only by imposition of the no fluid slip condition at its boundaries VACPRP usually 199 which is the IMAT assigned to a fictitious solid which prevents fluid from entering its space but exerts no frictional effect How Earth interprets the entries in the table As already mentioned lines with blanks in columns 1 and 2 are treated as comment lines blank lines are ignored Active lines are in free format and contain 6 or 7 entries fields Spaces or commas may be used as field separators Fields 2 7 may contain a constant or one of the GRND1 GRND9 flags Any property law available from GREX may be specified through PROPS Thus when placed in the DENSity column GRND1 sets DENS RHO1A RHO1B h1 where h1 is the enthalpy GRND2 sets DENS 1 RHO1A RHO1B h1 GRND3 sets DENS RHO1A p1 PRESS0 RHO1B RHO1C GRND4 sets DENS RHO1A RHO1B t1 where t1 is temperature GRND5 sets DENS RHO1B p1 PRESS0 t1 where p1 is pressure The values in the corresponding lines are therefore those of RHO1A RHO1B and RHO1C as appropriate When placed in the VISCosity column GRND1 sets VISC ENULA ENULB t1 where t1 is phase 1 temp GRND2 sets VISC ENULA ENULB t1 ENULC t1 2 GRND3 sets VISC ENULA ENULB t1 ENULC GRND4 sets VISC ENULA LGEN1 ENULB 1 0 2 0 RHO GRND5 sets VISC ENULA ENULB SQRT LGEN1 RHO GRND6 sets VISC ENULA t1 1 5 ENULB t1 RHO Any constants required must be specified on the following active lines these constants having the same definitions as in the GREX formulae Thus for density GRND3 Isentropic Gas Law the constants have the same definitions as RHO1A RHO1B and RHO1C for RHO1 GRND3 If

    Original URL path: http://www.cham.co.uk/phoenics/d_polis/d_enc/props.htm (2016-02-15)
    Open archived version from archive

  • How to make GROUND coding compatible with Parallel PHOENICS
    real sums a single real value over all processors and sends the global sum back to all processors NPROC is the number of processors always 1 for sequential MYID is the number of the current processor The master processor has the ID number 0 In sequential runs this is always 0 Example 2 This example shows how to sum up the sources in this case of mass over all patches to find the total mass inflow The problem lies in that on each processor the sequence of patches may be different as not all patches will exist on all processors However when summing across processors the loop indices must be in step otherwise the summation will fail and the run will stall In the example code the following variables and routines are used NPROC the number of processors Will be 0 for a parallel run GD NUMPAT this is the total number of patches in the global domain NUMPAT is the number of patches on the current processor or in a sequential run GD INDPAT iglob 1 this returns the local patch index for the global patch iglob If the value returned is 0 the patch does not exist on the current processor PGETCV iglob ivar coef val this returns the COefficient and VALue for variable ivar for global patch iglob If the coefficient is returned as 999 0 no COVAL exists for this variable at this patch GLSUM real which sums a single real value over all processors and sends the global sum back to all processors MYID is the number of the current processor The master processor has the ID number 0 In sequential runs this is always 0 Head of GROUND file SUBROUTINE GROUND INCLUDE phoenics d includ farray INCLUDE phoeclos d includ d earth parvar INCLUDE phoenics d includ satear INCLUDE phoenics d includ grdloc INCLUDE phoenics d includ satgrd INCLUDE phoenics d includ grdear INCLUDE phoenics d includ grdbfc INCLUDE phoenics d includ parear Group 19 Section 7 Coding Parallel specific code is in red 197 CONTINUE C SECTION 7 Finish of sweep C Calculate overall mass inflow IF NPROC GT 1 THEN ILIM GD NUMPAT ELSE ILIM NUMPAT ENDIF FMASIN 0 0 DO I 1 ILIM loop over global or local patches IF NPROC GT 1 THEN IR GD INDPAT I 1 get local index IR for global patch no I ELSE IR I in sequential local and global are the same ENDIF IF NPROC GT 1 THEN CALL PGETCV I R1 GCO GVAL get GO and VAL for Mass ELSE CALL GETCOV NAMPAT IR R1 GCO GVAL get GO and VAL for Mass ENDIF IF QEQ GVAL 999 CYCLE no COVAL for mass so skip to next patch IF IR LT 0 THEN SORCE 0 0 patch does not exist on this processor ELSE CALL GETSO IR R1 SORCE get mass source for local patch IR ENDIF IF NPROC GT 1 CALL GLSUM SORCE sum over all processors IF SORCE GT 0 0

    Original URL path: http://www.cham.co.uk/phoenics/d_polis/d_enc/para1.htm (2016-02-15)
    Open archived version from archive

  • ENC_Q1.HTM
    setting of the value of the variable FIINIT PRPS entering fiinit prps at the keyboard will elicit Suppose now that the user wishes to replace steel by copper first establishing which integer to use Then entering copper at the keyboard will reveal So as to make the change the user should then type fiinit prps copper or fiinit prps 103 and will see on the screen If the interactive session is now closed by pressing the F7 key and the resulting Q1 file is inspected in any editor it will be found that its last few lines are now as follows showing that as is true of all such interactions new instructions are added to the bottom of the file FIINIT PRPS STEEL To require properties of steel to be used PATCH minXface WEST 1 1 1 1 1 1 1 1 to locate the low x face PATCH maxXface WEST NX NX 1 1 1 1 1 1 to locate the high x face COVAL minXface TEM1 FIXVAL 0 0 to fix the values of both faces COVAL maxXface TEM1 FIXVAL 0 0 to zero PATCH HEATER volume 1 nx 1 1 1 1 1 1 to show that the volumetric heat flux extends from low x to high i e from 1 to nx COVAL HEATER TEM1 FIXFLU 1 e3 to fix the heat flux 1kW m 3 FIINIT PRPS COPPER STOP If now the solver is run by way of the command RUNEAR it will be found that the RESULT file now contains the lines Flow field at ITHYD 1 IZ 1 ISWEEP 1 ISTEP 1 Field Values of KOND 3 810E 02 3 810E 02 3 810E 02 3 810E 02 3 810E 02 IX 1 21 41 61 81 Field Values of PRPS 1 030E 02 1 030E 02 1 030E 02 1 030E 02 1 030E 02 IX 1 21 41 61 81 Field Values of TEM1 2 500E 09 2 073E 03 3 097E 03 3 071E 03 1 995E 03 IX 1 21 41 61 81 They show that the increase in thermal conductivity to 381 0 from 43 0 has produced a proportionat reduction in temperature as is to be expected the heat input having been left unchanged 5 3 Use of the Satellite s built in editor Let us now suppose that the user wishes to increase the heat input ten fold He could do so during a text interactive session by entering the line COVAL HEATER TEM1 FIXFLU 1 e4 This line would then appear at the bottom of the screen and since Satellite reads and interprets lines in the Q1 from top to bottom would over ride the higher up line However invocation of the Satellite s built in editor enables the higher up line to be edited directly Thus entering lb meaning list from the bottom in interactive mode elicits the screen shown here Evidently the line to be changed is number 76 The built in editor has no replace command therefore the user must type d76 so as to delete the line followed by i75 RETURN COVAL HEATER TEM1 FIXFLU 1 e4 RETURN RETURN Typing lb again will show that line 76 has indeed been replaced in the desired manner and when the solver is run again the temperatures will be found to have increased ten fold as expected The built in text editor is somewhat primitive as has been admitted but it has one advantage over a text editor it edits not the q1 but the internal to satellite instruction stack It can therefore see and allow the user to change instructions which the satellite reads by default before it reads the Q1 What these instructions are can be seen by issuing successively the commands L1 15 L16 30 L30 45 etcetera so as to list them all fifteen lines at a time The interested reader is free to study these but no further comments will be made here 5 4 Use of the VR editor The Virtual Reality Editor is activated by for example issuing the command RUNVRE wherein VRE stands for Virtual Reality Editor This editor is intended to assist users who are not conversant with PIL to write Q1 files for them and indeed it does so However in the course of time it has acquired the propensity to do much more Specifically when supplied with a user written Q1 file and nothing more it re writes it in its own dialect of PIL with both advantages and disadvantages some of which will now be discussed Let the Q1 which it reads be the first text edited Q1 which was discussed above First it is instructive to look at the Q1 which the VR Editor writes when it is simply opened and closed without the user s having made any modification to the data whatsoever It is shown here with interspersed comments in brown font explaining its differences from the Q1 described above with which the VR Editor started TALK T RUN 1 1 Q1 created by VDI menu Version 2008 Date 06 11 08 CPVNAM VDI SPPNAM Core These are defaults of the VR Editor referred to as VRE from now on SPPNAM Core means that this is NOT a Special Purpose Program For present purposes there is no need to comment on every item Readers who are interested in disregarded items such as CPVNAM can find explanations in the PHOENICS Encyclopaedia Echo DISPLAY USE settings DISPLAY Simulation of heat conduction in a steel slab of 0 1 m thickness internallly heated by 1 kW m 3 of electric power with both its faces held to 0 0 deg Celsius ENDDIS IRUNN 1 LIBREF 0 Group 1 Run Title TEXT No title has been set for this run Group 2 Transience STEADY T The human editor knew that steady flow is the default and therefore made no mention of the logical variable STEADY but VRE is here seen to be more punctilious Groups 3 4 5 Grid Information Overall number of cells RSET M NX NY NZ tolerance RSET M 100 1 1 1 000000E 05 This is an example of VRE s dialect of PIL The 100 is NX the 1 1 are NY NZ the three integers being the numbers of intervals in the x y and z directions the defaults which the Human Editor henceforth H E did not need to mention 1 000000E 05 is the default tolerance which will not be explained here It should be noted however that neither XULAST nor THICK appear either explicitly or implicitly VRE prefers numbers to characters It may also be noticed that VRE is not economical in its printing practices We humans might find 1 E 5 sufficient but VRE prints 1 000000E 05 Group 6 Body Fitted coordinates Group 7 Variables STOREd SOLVEd NAMEd ONEPHS T Non default variable names NAME 148 KOND NAME 149 PRPS NAME 150 TEM1 Solved variables list SOLVE TEM1 Stored variables list STORE PRPS KOND H E did not need to say that this was a default one phase phenomenon and H E did not care into which member ot the NAME array TEM1 was placed Group 8 Terms and Devices Group 9 Properties Domain material index is 111 signifying STEEL at 27 deg c C 1 SETPRPS 1 111 ENUT 0 000000E 00 DRH1DP 5 000000E 12 DVO1DT 3 700000E 06 PRNDTL TEM1 4 300000E 01 Here the VR Editor has used the command SETPRPS 1 111 signifying set the properties of the first phase material to be those of the material with index number 111 It is the equivalent of H E s command fiinit prps steel Both are legitimate PIL statements Once again VRE uses the harder to read long form rather than the briefer equivalent ENUT 0 DRH1DP 5 E 12 DVO1DT 3 7E 06 PRNDTL TEM1 4 3E 01 Group 10 Inter Phase Transfer Processes Group 11 Initialise Var Porosity Fields FIINIT KOND 1 001000E 10 FIINIT PRPS 1 000000E 02 FIINIT TEM1 1 001000E 10 No PATCHes used for this Group INIADD F Group 12 Convection and diffusion adjustments No PATCHes used for this Group Group 13 Boundary and Special Sources PATCH MINXFACE WEST 1 0 0 0 0 0 1 1 COVAL MINXFACE TEM1 FIXVAL 0 000000E 00 PATCH MAXXFACE WEST 2 0 0 0 0 0 1 1 COVAL MAXXFACE TEM1 FIXVAL 0 000000E 00 PATCH HEATER VOLUME 0 0 0 0 0 0 1 1 COVAL HEATER TEM1 FIXFLU 1 000000E 03 Here is something interesting the indicial arguments of the PATCH command are different from those in the original Q1 This will be explained below The arguments of COVAL are the same however albeit with a tiresome excess of spaces and zeroes There follow several groups in which both H E and VRE have tacitly adopted the default values EGWF T Group 14 Downstream Pressure For PARAB Group 15 Terminate Sweeps LSWEEP 1 RESFAC 1 000000E 03 Group 16 Terminate Iterations Group 17 Relaxation Group 18 Limits Group 19 EARTH Calls To GROUND Station Group 20 Preliminary Printout Group 21 Print out of Variables Group 22 Monitor Print Out NPRMON 100000 NPRMNT 1 Group 23 Field Print Out and Plot Control NPRINT 100000 ISWPRF 1 ISWPRL 100000 No PATCHes used for this Group Group 24 Dumps For Restarts Now begin some VRE only settings GVIEW has no counterpart in the original Q1 which was not concerned as GVIEW is with displaying the domain grid and objects visually on the computer screen GVIEW P 0 000000E 00 1 000000E 00 0 000000E 00 GVIEW UP 1 000000E 00 0 000000E 00 0 000000E 00 DOM SIZE 1 000000E 01 1 000000E 00 1 000000E 00 The first 1 000000E 00 of SIZE of DOM the domain is the XULAST set by the user in his Q1 of which the block occupies the whole of the domain The other two are the default values of YVLAST and ZWLAST Of course the line would be easier to inderstand and equally acceptable to the SATELLITE if it were printed as DOM SIZE XULAST YVLAST ZWLAST DOM SCALE 1 000000E 00 1 000000E 00 1 000000E 00 DOM INCREMENT 1 000000E 02 1 000000E 02 1 000000E 02 GRID BOUNDS F F F F F F GRID RSET X 1 99 1 000000E 00 GRID RSET X 2 1 1 000000E 00 Above is seen the way in which the VR editor thinks of the 100 interval set by H E namely as 99 plus 1 The reason is that the writer of the original Q1 file probably through inadvertence gave the patch on the east face the type west This made no difference to the solution because the east and west areas of the cell have the same value but the VR Editor thought that it might have some significance GRID RSET Y 1 1 1 000000E 00 GRID RSET Z 1 1 1 000000E 00 Below it appears that the low x and high x patches which H E inserted have been converted into Virtual Reality objects Their positions are now expressed in terms of real number distances instead of integer indices OBJ NAME MINXFACE OBJ POSITION 0 000000E 00 0 000000E 00 0 000000E 00 OBJ SIZE 0 000000E 00 1 000000E 00 1 000000E 00 OBJ GEOMETRY default OBJ ROTATION24 1 OBJ TYPE USER DEFINED OBJ NAME MAXXFACE OBJ POSITION 9 900000E 02 0 000000E 00 0 000000E 00 OBJ SIZE 0 000000E 00 1 000000E 00 1 000000E 00 OBJ GEOMETRY default OBJ ROTATION24 1 OBJ TYPE USER DEFINED STOP without changing the relative geometrical positions of the physically important physical features Nevertheless it can be disconcerting for unless certain precautions are taken the re writing of the Q1 can involve loss of some important information which H E has supplied How this comes about is reported at length here Another example case 116 Core Input Library case 116 was discussed above and it exhibited the PIL do loop feature for setting porosities It is interesting to observe what occurs when this Q1 is read into the VR Editor The Q1 which the VR editor creates as output replacing and leaving no back up of the one which it read has no do loop Instead the implications of the initial do loop are expressed thus OBJ NAME HPOR1 OBJ POSITION 0 000000E 00 0 000000E 00 2 200000E 00 OBJ SIZE 1 000000E 00 5 000000E 02 3 400000E 00 OBJ GEOMETRY cube14 OBJ ROTATION24 1 OBJ TYPE BLOCKAGE OBJ MATERIAL 199 Solid allowing fluid slip at walls OBJ NAME HPOR2 OBJ POSITION 0 000000E 00 5 000000E 02 2 600000E 00 OBJ SIZE 1 000000E 00 5 000000E 02 2 600000E 00 OBJ GEOMETRY cube14 OBJ ROTATION24 1 OBJ TYPE BLOCKAGE OBJ MATERIAL 199 Solid allowing fluid slip at walls OBJ NAME HPOR3 OBJ POSITION 0 000000E 00 1 000000E 01 3 000000E 00 OBJ SIZE 1 000000E 00 5 000000E 02 1 800000E 00 OBJ GEOMETRY cube14 OBJ ROTATION24 1 OBJ TYPE BLOCKAGE OBJ MATERIAL 199 Solid allowing fluid slip at walls OBJ NAME HPOR4 OBJ POSITION 0 000000E 00 1 500000E 01 3 400000E 00 OBJ SIZE 1 000000E 00 5 000001E 02 9 999998E 01 OBJ GEOMETRY cube14 OBJ ROTATION24 1 OBJ TYPE BLOCKAGE OBJ MATERIAL 199 Solid allowing fluid slip at walls OBJ NAME HPOR5 OBJ POSITION 0 000000E 00 2 000000E 01 3 800000E 00 OBJ SIZE 1 000000E 00 4 999997E 02 1 999998E 01 OBJ GEOMETRY cube14 OBJ ROTATION24 1 OBJ TYPE BLOCKAGE OBJ MATERIAL 199 Solid allowing fluid slip at walls These statements are very different in form from those of the original Q1 and indeed porosity makes no appearance Instead the same fluid flow blocking effect achieved by the formerly specified field of porosity is here effected by introduction of objects to which the the Editor has automatically assigned the names HPOR1 etc Further the positions of these objects are specified in terms of geometrical distances rather than by reference to grid indices This has the advantage that they will retain their positions and sizes in space even though the fineness of the grid is increased However how the porosity was at first defined has been lost sight of This loss is sometimes serious A source of further information The above discussion has concentrated on the difference between the various dialects of PIL which appear in differently created Q1s A much fuller account of Q1s written by the VR Editor can be found in the relevant section of TR326 accessed by clicking here 5 5 Use of Prelude The fifth means of Q1 writing involves use of the relatively new pre pre procesor of PHOENICS viz PRELUDE the module in the diagram shown at the start of this article It is seen there that PRELUDE receives information from the gateway shown on the left and passes it on in the form of a Q1 file to the Satellite Some extracts from such a Q1 now follow together with some interpolated comments in brown font The flow scenario to which the Q1 relates is similar to that which will be discussed in section 6 1 below namely that of the release of noxious gas into the atmosphere and it will be seen that PRELUDE is able to write a parameterised Q1 the nature and merits of which are the subject of the whole of section 6 TALK T RUN 1 1 CPVNAM VDI SPPNAM Core Group 1 Run Title TEXT case1 save1begin PRELUDE uses the standard Group structure and uses the save begin and save end protected mode markers REAL RELDIAM RELANGL WINDANGL WINDVEL GASPR FLOORCO REAL MOLWT WALLHIGH SCALE OUTDIST INDIST WALLTHCK REAL DOMWIDE WALLDIST DOMLONG RELHIGH PIPEZPOS PIPEDIAM CHAR UWIND TMODEL GASDEN GASVEL GASFLO PROFL REAL DOMHIGH INTEGER NZGRID NYGRID NXGRID CHAR VWIND VPROFL UPROFL PRELUDE starts by making declarations of variables above and then ascribing values to them below RELDIAM 025 Leak diameter NZGRID 35 number of Z cells RELANGL 90 Gas release angle degrees NYGRID 30 number of Y cells WINDANGL 0 angle degrees of wind relative to X axis NXGRID 50 number of cells in X WINDVEL 2 wind velocity at top of domain UWIND WINDVEL cos WINDANGL 3 14159 180 U velocity of wind The settings may be made by way of formulae See above and below Each setting may carry an explanatory comment after the exclamation mark GASPR 1 e5 pressure of gas above atmosphere TMODEL ke Turbulence model FLOORCO 0 005 friction coefficient on ground MOLWT 28 9 Molecular weight of gas GASDEN 1 189 MOLWT 28 9 gas density inferred from air GASVEL 2 GASPR GASDEN 5 gas velocity at escape GASFLO GASVEL GASDEN RELDIAM 2 3 14159 4 mass of gas e scaping WALLHIGH 2 5 Height of wall SCALE WALLHIGH scale of objects OUTDIST 14 SCALE distance downstream INDIST 2 5 SCALE distance from start of domain to gas leak WALLTHCK 0 2 SCALE thickness of wall DOMWIDE 12 SCALE Width of domain WALLDIST 7 5 SCALE distance from gas leak to wall DOMLONG INDIST WALLDIST OUTDIST Length of domain RELHIGH 0 4 SCALE Release height PIPEZPOS 0 4 SCALE Position of gas leak above ground PIPEDIAM 0 16 SCALE Pipe diameter DOMHIGH 3 5 SCALE Height of domain PROFL zg DOMHIGH 1 7 Profile of wind speed VWIND WINDVEL sin WINDANGL 3 14159 180 V velocity of w ind VPROFL VWIND PROFL Profile of Y velocity UPROFL UWIND PROFL Profile of X velocity save1end TEMP0 273 15 reference temperature deg K PRESS0 1 e5 reference pressure N m 2 LSWEEP 50 the last sweep number save1begin Grid dimension rules REAL NXCALC NYCALC NZCALC NXCALC NXGRID NYCALC NYGRID NZCALC NZGRID Domain size rules REAL DOMXSZ DOMYSZ DOMZSZ DOMXSZ DOMLONG DOMYSZ DOMWIDE DOMZSZ DOMHIGH save1end CONWIZ T GROUP 2 Transience time step specification GROUP

    Original URL path: http://www.cham.co.uk/phoenics/d_polis/d_enc/enc_q1.htm (2016-02-15)
    Open archived version from archive

    USE fil for which there is no keyboard equivalent are the PAUSE command will cause the program to halt until RETURN is pressed the UPAUSE n command will cause the program to halt for n seconds of a line any line having an asterisk as the first non blank character will be ignored the command MSG text string will display the text string the PAUSE UPAUSE and UREWIND commands permit control of the execution of the USE file the UTEXT and UMAGNIFY commands provide non interactive analogues of TEXT and MAGNIFY in order to permit fully automatic operation of USE files NOTE that only one USE file may be in use at any one time i e nesting of USE files is not allowed See also UPAUSE UREWIND UTEXT UMAGNIFY USEGRD Logical default T group 19 USEGRD the default setting T ensures access to the user portion of subroutine GROUND that follows the call to GREX If the user has not inserted his own sequences in GROUND the uneconomical repetition of the numerous control statements in GROUND can be prevented by setting USEGRD F USEGRX Logical default T group 19 USEGRX may be set to F to deactivate the call

    Original URL path: http://www.cham.co.uk/phoenics/d_polis/d_enc/use.htm (2016-02-15)
    Open archived version from archive

  • The PHOENICS Chronicle
    PHOENICS that have been presented around the world and are contained here to give further insight into how PHOENICS has developed Please click on one of the topics below for more information Early versions of PHOENICS later made available as shareware Developments 1992 1993 Developments 1993 1994 Developments 1995 1996 The introduction of Virtual Reality Versions 2 2 3 0 and 3 1 Front end Developments for PHOENICS 3 2

    Original URL path: http://www.cham.co.uk/phoenics/d_polis/d_chron/chron.htm (2016-02-15)
    Open archived version from archive

  • The GREX3 Subroutine
    DT Normally the time step is fixed by the TFRAC setting made in PIL but this option povides the opportunity for DT to be made a function of other calculated quantities or of some complicated distribution awkward to set in PIL It should be noted that the number of time steps is still fixed by TFRAC 1 Thus the PIL commands TFRAC 1 250 0 TFRAC 2 1 0 TLAST GRND will instruct EARTH to perform 250 time steps the size of each being determined by the setting of DT in group 2 When control returns to EARTH it sets TIM TIM DT Group 3 This group is CALLed at the start of the current z slab at the stage when the geometry is being calculated It is useful in parabolic calculations PARAB T to expand the x extent of the grid The EARTH CALL to this group is activated when AZXU GRND The user s job is to set the variable XRAT which is the ratio of the x extent at the current z slab to that of the previous slab Thereafter EARTH modifies all geometrical entities eg internodal distances cell face areas XULAST etc to conform with XFRAC Typically it is desired to make the domain width a function of the downstream distance of the current slab ZW For example XRAT RG 1 RG 2 ZW RG 3 ZW 2 XULAST gives a quadratic dependence The RGs are PIL set parameters More often it might be desired to set XRAT to vary with z so as to accommodate a boundary layer which would necessitate local determination of the width of the layer in order that edge velocities should be sufficiently close to the free stream values It should be noted that group 3 is called after group 5 where ZW is set so that in group 3 ZW is the current slab z ZWL stores the z location of the low face of the current z slab ie the ZW of the previous slab Group 4 Group 4 performs an exactly corresponding function for the y direction domain width YVLAST to that performed by group 3 for XULAST EARTH visits the group when AZYV is set to GRND in PIL Group 5 This group is visited by EARTH when AZDZ has been set LE GRND in SATELLITE it sets the step size DZ in parabolic calculations Two examples are provided in GREX3 activated by AZDZ GRND1 or AZDZ GRND2 They make the step size a fixed fraction RSG10 of the calculation domain widths XULAST and YVLAST respectively The user would need to provide coding here if the options provided in GREX3 were inadequate for his needs Group 6 This group is called from EARTH when UGEOM T at the start of the current IZ slab just after the current slab geometry eg inter nodal distances cell face areas etc has been set It therefore provides the possibility of amending these geometrical entities In non BFC calculations geometrical modifications are also often performed by amendment to the porosity factors When BFC equals T however the geometrical quantities are calculated and stored whole field at the start of the calculations they are multiplied by the porosity factors there once for all Thus this group provides opportunities for amendment of the geometrical quantities once BFC equals F GREX3 contains no example of the use of this Group but a CALL to GXPORA from GROUP 19 has a similar effect Group 7 This Group is not entered Group 8 This group contains 15 sections Provision has been made in Group 8 of GROUND for extensive intervention in the procedures of formulation and solution of the finite domain equations which are central to the flow simulation process of PHOENICS Whoever wishes to use this will find helpful advice in the comments which appear in group 8 of GREX3 and specifically in sections 8 to 14 These comments explain what must be done to ensure that the relevant sections of GREX3 and GROUND if USEGRD T are to be entered logical variables such as UCONV UDIFF etc are to be set TRUE in the SATELLITE These variables allow the user to set in accordance with whatever rule he prefers the convective coefficients the diffusive coefficients the convection neighbour values the diffusion neighbour values the two components of the linearised source terms any of the coefficients in the variable correction equation the solution procedure or the results of that procedure Values of the coefficients neighbour values etc will already have been set by EARTH in accordance with the standard prescription at the time at which control passes to GROUND What these values are can be determined by the activation of the calls to the PRN subroutine which have been deactivated by C s in the first column see the listing of GREX3 Even if the user decides he does not want to activate these statements he will find the way in which the various quantities are referred to be instructive about how the functions L0F and L0FZ should be used in arguments of other functions for example FN0 when values are to be restored to EARTH Group 9 This group originally contained 13 sections all of which were concerned with setting material properties or other auxiliary quantities used in calculations Nowadays these calls are made directly from withn EARTH so this group is empty Group 10 This group contains four sections all of which are concerned with setting quantities that determine the intensity of inter phase transport Thus section 1 sets the coefficient of inter phase diffusion of momentum ie friction which is also used after multiplication by CINT for diffusion of other variables when their CINTs are not equal to GRND Section 2 sets the inter phase convection ie the mass transfer rate Sections 3 and 4 are used to set phase to interface diffusion transfer coefficients normally for non velocity variables an isotropic velocity transfer coefficient being set in section 1 The reader is advised at this stage to study GREX3 The listing shows how PIL is used to instruct EARTH to visit each section eg CMDOT LE GRND for the interphase friction coefficient and the index or index function which permits GROUND to refer to the storage location of the quantity in EARTH The coefficients of the diffusive transfer of momentum must be set in accordance with its definition Total interphase friction force for the cell Velocity difference between the two phases The coefficient of the diffusive transport of the other PHI variables must be in accordance with the definition Diffusive flux of PHI to interface for the cell PHI difference between the bulk of the phase and its interface value PHINT The first two sections are called at the start of the hydrodynamic iteration of the current IZ slab When visited EARTH expects GROUND to return an array of values in the F array segment address locations determined by the indices INTFRC and INTMDT As an example consider an inter phase friction coefficient equal to a constant CFIP1A times the in cell mass of the first phase times the in cell volume fraction of the second phase The following statement inserted in section 1 effects this dependence CALL FN21 INTFRC MASS1 R2 0 0 CFIP1A The subroutine FN21 y x1 x2 a b has the following mathematical significance y a b x1 x2 For each cell in the current IZ slab the index MASS1 refers to the EARTH store of the mass of phase one in each cell at the current slab An equivalent but more understandable sequence is affected by see also previous section L0FIP L0F INTFRC L0MAS L0F MASS1 L0R2 L0F R2 NXNY NX NY DO 109 I 1 NXNY 109 F L0FIP I CFIP1A F L0MAS I F L0R2 I In the above sequence the first three statements locate the zero locations in the F array of the friction coefficients the mass of phase 1 in the cell and the volume fraction of the second phase Another technique is to use the subroutine GETYX to get and store locally the arrays for MASS1 and R2 to calculate and store the required result in the array GFIP and to set the EARTH array to the data contained in it An example now follows CALL GETYX MASS1 GM1 NYDIM NXDIM CALL GETYX R2 GR2 NYDIM NXDIM DO 102 IX 1 NX DO 102 IY 1 NY 102 GFIP IY IX CFIP1A GM1 IY IX GR2 IY IX CALL SETYX INTFRC GFIP NYDIM NXDIM The arrays GFIP GM1 and GR2 are dimensioned to NYDIM NXDIM which must be greater than NY NX respectively at the top of the subroutine This technique although familiar to users of PHOENICS 81 is not recommended because the first two methods are more economical Sections 3 and 4 are CALLed when the interphase terms are being assembled for variable PHI when CINT PHI is less than equal to GRND Thus different formulae can be supplied for different dependent variables EARTH sets the GROUND variable INDVAR so that the FORTRAN can distinguish one PHI entry from another The indices CO1I and CO2I permit the F array zero locations to be deduced as L0F CO1I and L0F CO2I GREX3 supplies options for CMDOT CFIPS and CINT INDVAR which are described under their respective entries in chapter 2 Group 11 This group is for setting non uniform initial conditions for variables that are stored whole field This group is visited by EARTH for variables for which the fourth argument of INIT set in the SATELLITE is GRND see INIT for background information EARTH visits group 11 for the field values of variable INDVAR over the current patch at the current IZ step The field values are to be set in EARTH at a segment address located by means of the integer index VAL The following example will clarify what has to be done Suppose that it is desired to initialise the w velocity field to a parabolic profile over the last half of the domain the PIL commands PATCH LASTHALF INIVAL 1 NX 1 NY NZ 2 NZ 1 1 INIT LASTHALF W1 0 0 GRND instruct EARTH to visit group 11 of GROUND for an array of values for the field W1 at each slab within the sub domain indicated by arguments 3 to 8 of PATCH Prior to calling group 11 EARTH sets NPATCH 1 8 LASTHALF INDVAR W1 IXF 1 IXL NX IYF 1 IYL NY and IZ contains the current z slab that EARTH is considering The following coding does what is needed in group 11 IF NPATCH EQ LASTHALF THEN IF INDVAR EQ W1 THEN CALL FN4 VAL YG2D RG 1 RG 2 RG 3 ENDIF ENDIF RETURN The subroutine FN4 y x a b c has the mathematical significance y a b x c x 2 for each cell in the current PATCH at IZ The index YG2D refers to the EARTH array of length NX NY elements that contains the y coordinate of the cell centres at the slab It should be noted that RG 1 RG 2 and RG 3 are PIL parameters An equivalent but more transparent sequence is effected by first determining the segment address of VAL and YG2D and then providing a DO loop that sets the field directly L0VAL L0F VAL L0Y L0F YG2D DO 111 IX IXF IXL DO 111 IY IYF IYL ICELL IY IX 1 NY XX F L0Y ICELL 2 111 F L0VAL ICELL RG 1 RG 2 F L0Y ICELL 1 RG 3 XX Yet another technique to achieve the same is to use the subroutine GETYX to get and store locally the array YG2D to overwrite this local array with the array of values required and then to set the EARTH store of VAL equal to the data in this array thus CALL GETYX YG2D GY NYDIM NXDIM DO 111 IX IXF IXL DO 111 IY IYF IYL XX GY IY IX 2 111 GY IY IX RG 1 RG 2 GY IY IX RG 3 XX CALL SETYX VAL GY NYDIM NXDIM where GY is an array dimensioned to NYDIM NXDIM at the top of subroutine GROUND NYDIM NXDIM must be geater than or equal to NY NX respectively Group 11 can be visited for any number of variables for a given PATCH for which non uniform fields are wanted Any number of PATCHes may be used The user must use the parameters NPATCH INDVAR and IZ to distinguish one patch from another one variable from another and one slab from another Group 12 Group 13 Group 13 of GROUND is the place where the user can provide non linear sources and boundary condition information for PATCHes of the domain for variables identified by COVAL The PIL instructions PATCH name type ixf ixl itf itl COVAL name PHI GRND instruct EARTH to visit group 13 of GROUND for an array of coefficients for each z slab indicated for the variable PHI The index L0F CO gives the zero location of the appropriate segment of the F array into which the coefficients must be put The PIL instructions PATCH name type ixf ixl itf itl COVAL name PHI GRND correspondingly instruct EARTH to visit group 13 of GROUND for an array of values The PIL instructions PATCH name type ixf ixl itf itl COVAL name PHI GRND GRND instruct EARTH to visit group 13 once for an array of COefficients and again for an array of VALues The PIL instructions PATCH name type ixf ixl itf itl COVAL name PHI GRND GRND COVAL name PHIA 0 GRND COVAL name PHIB GRND 0 causes EARTH to visit groups 13 for COs and VALs for variable PHI VALs for variable PHIA and COs for variable PHIB In this case there are four CALLs from EARTH for the PATCH in question for each slab IZ in the range of arguments 7 and 8 in PATCH At each slab the COefficient and VALue arrays need to be set over the extent ixf to ixl iyf to iyl ie ixl ixf 1 iyl iyf 1 values are to be set Before EARTH calls group 13 it sets NPATCH character 8 IZ and INDVAR to the current PATCH name the current IZ considered and the current variable in question respectively Reference to these variables in the FORTRAN coding can distinguish between the possibilities selected Group 13 of GROUND is subdivided into 22 sections The first 11 sections are provided for the setting of COefficient array options and the last 11 are provided for setting VALue array options according to the following scheme ISC 1 Section 1 COVAL name PHI GRND ISC 2 Section 2 COVAL name PHI GRND1 ISC 3 Section 3 COVAL name PHI GRND2 ISC 4 Section 4 COVAL name PHI GRND3 ISC 5 Section 5 COVAL name PHI GRND4 ISC 6 Section 6 COVAL name PHI GRND5 ISC 7 Section 7 COVAL name PHI GRND6 ISC 8 Section 8 COVAL name PHI GRND7 ISC 9 Section 9 COVAL name PHI GRND8 ISC 10 Section 10 COVAL name PHI GRND9 ISC 11 Section 11 COVAL name PHI GRND10 ISC 12 Section 12 COVAL name PHI GRND ISC 13 Section 13 COVAL name PHI GRND1 ISC 14 Section 14 COVAL name PHI GRND2 ISC 15 Section 15 COVAL name PHI GRND3 ISC 16 Section 16 COVAL name PHI GRND4 ISC 17 Section 17 COVAL name PHI GRND5 ISC 18 Section 18 COVAL name PHI GRND6 ISC 19 Section 19 COVAL name PHI GRND7 ISC 20 Section 20 COVAL name PHI GRND8 ISC 21 Section 21 COVAL name PHI GRND9 ISC 22 Section 22 COVAL name PHI GRND10 In any particular section coefficient or value arrays can be set for any number of different PHIs for which there are COVALs The possibilities offered by this feature are heavily exploited in GREX3 where an additional degree of freedom is added by the recognition of special PATCH names The beginner to GROUND is advised to use GRND only and hence to set his coefficients and values in section 1 and section 12 of group 13 respectively In what follows two examples are provided of group 13 coding The reader can examine group 13 of GREX3 and the GX library subroutines called from there for further examples The first example is one in which a known internal heat source per unit volume is present over a restricted portion of the domain namely at IX 3 to 7 IY 2 to 20 and IZ 3 to 6 Suppose that this heat source per unit volume q is known to vary with position as follows q ax by cz This is not a non linear source for it does not depend upon any solved quantity It is however non uniform and without the possibility of GROUND coding would necessitate 7 3 1 20 2 1 6 3 1 580 separate PATCHs to set the heat flux in the cells covered The following PIL commands instruct EARTH to look for an array of values of the PATCH instead PATCH HEAT VOLUME 3 7 2 20 3 6 5 10 COVAL HEAT H1 FIXFLU GRND The last two arguments of PATCH dictate that the source will be applied only during time steps 5 to 10 inclusive The coding in group 13 to effect the formula is as follows IF NPATCH 1 4 EQ HEAT THEN IF INDVAR EQ H1 THEN CALL FN10 VAL XG2D YG2D RG 3 ZW RG 1 RG 2 ENDIF ENDIF RETURN The subroutine FN10 y x1 x2 a b c has the following mathematical significance y a b x1 c x2 for all cells in the zone IXF to IXL IYF to IYL at the current slab RG 1 RG 2 and RG 3 are PIL variables representing p q and r It should be noted that VAL is not multiplied by 1 0E10 i e 1 0 FIXFLU this

    Original URL path: http://www.cham.co.uk/phoenics/d_polis/d_enc/grex3.htm (2016-02-15)
    Open archived version from archive


web-archive-uk.com, 2017-12-13