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  • infrmobj.htm
    the coordinate system of the sphere coincides with the coordinate system of the calculation domain However when the calculation is being carried out with a cylindrical polar coordinate grid the cartesian coordinate system of the sphere has its origin at the bottom left hand corner of a rectangular box which circumscribes a cylinder of radius RINNER YVLAST In this case cartesian coordinates xc and yc are related to the polar coordinates xp and yp by the relations xc yvlast rinner yp rinner sin xp and yc yvlast rinner yp rinner cos xp The Z coordinates of the origins and the directions of Z axes of both coordinate systems coincide with one another Library case 772 creates an In Form object namely a sphere with its centre on the axis of a polar grid by means of INFOB at PATCH1 is SPHERE 10 10 10 5 with INFOB 1 The PHOTON plot displayed here reveals the result In this case it may be noted xce yce and zce are declared as character variables This is the preferable procedure when the possible use of formulae as arguments is to be provided for The ELIPSOID function The format governing the use of ELLIPSOID in INFOB statements is indicated by the following example INFOB at ELLPAT1 is ELLPSD arguments with INFOB ELL1 where ELLPAT1 and ELL1 are names chosen freely by the user The arguments in question are as follows ELLPSD x0 y0 z0 xrad yrad zrad alpha beta theta where x0 X coordinate of the centre of the ellipsoid in meters y0 Y coordinate of the centre of the ellipsoid in meters z0 Z coordinate of the centre of the ellipsoid in meters xrad X direction radius in meters yrad Y direction radius in meters zrad Z direction radius in meters alpha angle rotating around x axis in radians beta angle rotating around y axis in radians theta angle rotating around z axis in radians Library case 384 illustrates the use of the ELLPSD function for the creation of an ellipsoid in a cubical domain with all its rotations equal to 0 25 radians by means of the following statements inform11begin stored of mark at patch1 is 1 0 with infob 1 MARK object initial of prps is 100 with infob 1 initialise PRPS real x0 y0 z0 xs ys zs al be th declarations x0 xulast 4 x y z position of ellipsoid y0 yvlast 4 z0 zwlast 4 xs xulast 2 x y z radius of ellipsoid ys yvlast 3 zs zwlast 4 al 0 25 alpha beta theta angles of coordinate system be 0 25 of ellipsoid th 0 25 infob at patch1 is ellpsd x0 y0 z0 xs ys zs al be th with infob 1 inform11end An image representing the ellipsoid created by core input file library case 384 can be seen by clicking here Another example of the use of ellipsoid objects is core library case 162 wherein the ellipsoid is given such an extremely large y direction radius that within the domain of study it can be regarded as a cylinder It is indeed used there to represent a cylindrical pipe with an aperture in its walls from which gas is released into the atmosphere A fuller description of the situation can be found by clicking here c The basic cell cutting i e sub grid shapes Sub grid objects are those of which one of the dimensions is smaller than that of the computational grid The three basic shapes of this kind are POINT LINE and PLANE and to each there corresponds an In Form function The POINT function The format governing the use of POINT in INFOB statements is indicated by the following example INFOB at PNTPAT1 is POINT arguments with INFOB PNT1 options where PNTPAT1 and PNT1 are names chosen freely by the user The arguments in question are as follows POINT x0 y0 z0 nomdiam where x0 X coordinate of the point in meters y0 Y coordinate of the point in meters z0 Z coordinate of the point in meters nomdiam nominal diameter of the point The setting of point objects is exemplified in Core Library case 385 as seen by clicking here The LINE function The format governing the use of Line in INFOB statements is indicated by the following example INFOB at LINPAT1 is POINT arguments with INFOB LIN1 optionsV where LINPAT1 and LIN1 are names chosen freely by the user The arguments in question are as follows LINE x0 y0 z0 x1 y1 z1 nomdiam where x0 X coordinate of the start point in meters y0 Y coordinate of the start point in meters z0 Z coordinate of the start point in meters x1 X coordinate of the end point in meters y1 Y coordinate of the end point in meters z1 Z coordinate of the end point in meters nomdiam nominal diameter of the line The setting of line objects is exemplified in Core Library case 385 as seen by clicking here The PLANE function The format governing the use of PLANE in INFOB statements is indicated by the following example INFOB at PLAPAT1 is PLANE arguments with INFOB PLA1 options where PLAPAT1 and PLA1 are names chosen freely by the user The arguments in question are as follows PLANE where x0 X coordinate of 1st vertex in meters y0 Y coordinate of 1st vertex in meters z0 Z coordinate of 1st vertex in meters x1 X coordinate of 2nd vertex in meters y1 Y coordinate of 2nd vertex in meters z1 Z coordinate of 2nd vertex in meters x2 X coordinate of 3rd vertex in meters y2 Y coordinate of 3rd vertex in meters z2 Z coordinate of 3rd vertex in meters x3 X coordinate of 4th vertex in meters y3 Y coordinate of 4th vertex in meters z3 Z coordinate of 4th vertex in meters nomdiam nominal thickness of the plane Not all shapes are permissible as shown here Further if the user inadvertently selects four

    Original URL path: http://www.cham.co.uk/phoenics/d_polis/d_enc/infrmobj.htm (2016-02-15)
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  • Chapter 1: The PHOENICS object concept
    from the beginning but better late than never The new practice is especially useful when the objects are characterised in practice by rather few parameters which may well remain the same from case to case such as a perforated floor tile which has an unchanging flow versus pressure drop relation and is nearly always placed horizontally a standard size electronic equipment cabinet which always stands upright and is mainly characterized by its heat source or a standard size wall mounted heating panel which is mainly characterised by the temperature at which it is maintained Section 1 2 New thinking about objects and patches Changes of language assist changes of thinking Therefore the concept of the Phoenics Object file with the extension POB has been introduced Although in fact dat and pob files are treated in the same way by the PHOENICS satellite the former name is preferred for the old style geometry only files of which there are very many while the latter is ascribed to any file of which there are still rather few which contains non geometric attributes in addition The pob file is not the first to contain both geometric and non geometric information for the geo file produced by the Shapemaker modules did the same Moreover whereas the VR Editor could work only with imported shapes Shapemaker could create them AND assign attributes to the associated objects In order to simplify the user s task it has been decided to combine the capabilities of both the VR Editor and Shapemaker so that if the required shape already exists the appropriate dat file will be imported if it does not Shapemaker will be called on to make it even during the VR Editor session required non geometric attributes will be added by way of either Shapemaker or the VR Editor menus as the user finds convenient the resulting Phoenics Object will be stored for future re use in a POB file There have been other changes in thinking which are gradually taking effect One of these is the lessened tendency to attach patches to objects The reasons for the tendency and its lessening are as follows In the early days of PHOENICS PATCHes with their associated COVALs presented the only means of introducing initial and boundary conditions Thus if a solid rectangular grid fitting object was to be represented one initial value patch would be used so as to specify the material index i e PRPS value of each cell within the block Then six additional wall type patches would be created one for each surface to express the frictional influence of those surfaces on the flow This practice has been unnecessary for many years for the EGWF i e earth generated wall function feature enables the frictional influence to be deduced simply from knowledge of which cells contain fluid and which solid A related early days notion is the supposition that if the just specified rectangular object also provided a source of heat a distinct patch

    Original URL path: http://www.cham.co.uk/phoenics/d_polis/d_chron/ph361/chap1.htm (2016-02-15)
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  • CONWIZ : The 'Convergence-Promoting Wizard' for PHOENICS
    turbine combustor A somewhat tougher test of the capabilities of CONWIZ is provide by this case also a veteran by reason of its more numerous active physical processes including turbulence and chemical reaction Once again the effects of the standard and CONWIZ settings are compared by way of the graphical monitor plots which may be displayed by clicking below standard and conwiz This time the slower convergence of CONWIZ is more noticeable However it is gratifying to observe that convergence has been achieved with CONWIZ T as the only setting which the user has had to make It should also be remarked that although the maximum absolute corrections appear to fluctuate more wildly for CONWIZ their actual values are extremely small next Library case w802 the nuclear steam generator CONWIZ has not yet been taught anything specific about two phase flow it is therefore interesting to see what happens when it is presented with another classic case This is the nuclear steam generator which was the application which long ago led to both to the invention of the IPSA algorithm and to the creation of PHOENICS itself CONWIZ is being asked to tackle this problem without even being given a hint by way if FIINIT STEAM about the expected volume fractions of steam and water in the generator The next two pictures show the relevant monitor plots standard and conwiz Not bad for a beginner one might conclude although the levelling off of some residuals requires examining Since the selection of relaxation parameters for two phase flow is notoriously difficult this first time success of CONWIZ is especially encouraging next Library case b524 the Mizuki impeller CONWIZ has been kept in equal ignorance of the specific features of body fitted coordinate calculations which it therefore treats in the same way as those with cartesian or polar coordinates The results for the veteran Mizuki impeller problem are shown in the next two graphical monitor plots standard and conwiz Convergence is good for both the standard and the CONWIZ settings but the episode at the end of the CONWIZ run raises the question why However this question is as much about the credibility of the residual plots as it is about the success of CONWIZ Also interesting is what happens when the rotation speed is increased tenfold This is shown by the next pair of plots stan 10 and conw 10 Evidently CONWIZ handles the change without difficulty but the standard settings no longer procure convergence next Library case i205 temperatures in a computer room Convergence is particularly difficult to procure for flows with natural convection for sometimes differing false time steps may be required for the vertical direction velocity the horizontal velocities the temperature If CONWIZ can handle them well users of FLAIR the HVAC version of PHOENICS will be much relieved The next two picture provide some encouraging evidence in respect of library case i205 standard and conwiz It appears that CONWIZ performs quite as well as the standard settings next back or contents 5 How does CONWIZ work The main features of CONWIZ are as follows It starts by making guesses about reference values of length velocity density and temperature From these it deduces and sets some initial values of variables including the DVELDPs i e the rates of change of velocity with pressure difference at every point It sets linear under relaxation factors for all variables including the DVELDPs It sets maximum values to the increments per sweep for some variables In some circumstances it can improve its settings in the course of the computation next back or contents 6 How reliable is CONWIZ Does CONWIZ always work No However as the above examples have shown it often does pretty well When CONWIZ has failed to procure complete convergence it has sometimes transpired that there is some special instability promoter in the way in which the problem has been set up Fires represented as fixed heat sources regardless of flow conditions have led to solutions which not even CONWIZ can persuade to settle down CONWIZ has been in existence only since February 2004 and has not been receiving full time attention too much should therefore not yet be claimed for it Nevertheless to set CONWIZ T is certainly a wise thing to do at the start of a new calculation next back or contents 7 How can users participate in the promotion of convergence Although CONWIZ is ready to tackle any problem on its own it will respect user s settings and accept their assistance If users prefer to use false time step relaxation for any variable other than velocity CONWIZ will print a message questioning their wisdom but it will not change the settings It will however insist on using linear relaxation for velocities Any user set linear relaxation factor will be used in preference to its own User set VARMINs and VARMAXs will also be respected even if being too narrowly defined they distort the final solution next Probably the best thing a user can do in order to help CONWIZ in cases of difficulty is to use the new maximum absolute correction limitation by placing in the Q1 file such lines as SPEDAT MAXINC TEM1 R 10 0 This limits the maximum correction of temperature at any point in a singe sweep to 10 degrees The user can also instruct CONWIZ to start from user specified reference values by way of the following commands SPEDAT RLXFAC REFVEL R user set value SPEDAT RLXFAC REFLEN R user set value SPEDAT RLXFAC REFTEMP R user set value SPEDAT RLXFAC REFRHO R user set value Further if he or she is bold enough to use them further spedats will set upper and lower limits and relaxation factors for the individual DVELDPs This is however not advised Leave it to the wizard is the better rule to follow next back or contents 8 How can CONWIZ be further developed There is much scope for CONWIZ to improve its performance

    Original URL path: http://www.cham.co.uk/phoenics/d_polis/d_chron/ph361/chap2.htm (2016-02-15)
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  • TR006 - Chapter 3: Fluid-structure interactions
    force integrated over the surface of the body but only if STORE SHRX SHRY SHRZ appears in Q1 The total forces in the X Y and Z coordinate directions The moments of the total force about the X Y and Z axes The deduced point of application of the force Facetted objects are those which do not use cuboid geometry files By default the geometry files for BLOCKAGE and PLATE

    Original URL path: http://www.cham.co.uk/phoenics/d_polis/d_chron/ph361/chap3.htm (2016-02-15)
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  • TR006 - Chapter 5: FLAIR
    temperature of the IMMERSOL radiation model The clothing insulation clothing insulation is measured in clo clothing unit tog European unit of thermal insulation or m 2 k w 1 clo 0 155 m 2 k w 1 tog 0 645 clo The practical range is between 0 clo no clothing and 4 clo Eskimo clothing 1lb 0 454kg corresponds roughly to 0 15 clo with 0 6 clo and 1 0 clo being typical of summer and winter clothing respectively The default value is 0 6 clo The Metabolic Rate is measured in met metabolic units or W m 2 1 met 58 15 W m 2 The appropriate value depends on the activity being undertaken see ISO 7730 and ISO 8996 0 8 met reclining 1 0 met seated relaxed 1 2 met sedentary activity office dwelling school laboratory 1 6 met standing light activity shopping laboratory light industry 2 0 met standing medium activity shop assistant domestic work machine work 1 9 met walking on the level at 2 km h 2 4 met walking on the level at 3 km h 2 8 met walking on the level at 4 km h 3 4 met walking on the level at 5 km h The default value is 1 2 met The external work is the part of the metabolic rate that is used up in the activity being performed rather than contributing to the heat balance of the individual concerned It is usually taken as zero and should always be less than the metabolic rate The default value is 0 0 The relative humidity individual comfort is influenced by the humidity of the air which affect the heat loss through the skin It is often sufficient to specify a reasonable value for a particular environment but it is also possible to calculate the humidity as part of the simulation The default value is 50 5 2 3 Predicted percentage dissatisfied PPD PPD is an index defined in ISO 7730 that predicts the percentage of a large group of people who are likely to feel too warm or too cool i e the percentage of a large group of people who would vote for values other than 0 1 or 1 on the thermal sensation scale used for PMV The required input parameters are the same as for PMV The following pictures show the PPD predictions at head height on upper level of a shopping mall The one with no vents shows that almost 100 of people would feel too warm whereas the one with vents shows this percentage much smaller 5 2 4 Draught Rating The draught rating is defined in ISO 7730 as the percentage of people dissatisfied due to draught using the following equation PPDR 34 T a V 0 05 0 62 0 37 V I 3 14 where T a is the local air temperature V is the local air velocity and I is the local turbulence intensity in In Flair it is

    Original URL path: http://www.cham.co.uk/phoenics/d_polis/d_chron/ph361/chap5.htm (2016-02-15)
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  • TR006 - Chapter 8: "PHOENICS On-Line"
    PHOENICS On Line CHAM introduced a new PHOENICS online facility during January 2003 With the release of PHOENICS 3 6 it was made available for interactive use via the internet

    Original URL path: http://www.cham.co.uk/phoenics/d_polis/d_chron/ph361/chap8.htm (2016-02-15)
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  • imbal.htm
    the quantity in question if the flow is steady and if the solution is converged the printed out imbalance should be as close to zero as round off error permits Larger imbalances are therefore a measure of lack of convergence which it may be useful to know about In like circumstances except that the flow is transient the printed imbalance represents the contribution of the transient terms of the equations integrated over the patch volume If the patch encloses a volume of fluid within which a solid object is held at rest the imbalances of momentum in three different directions represent the forces exerted by the fluid on the body Implementation in PHOENICS If a patch name in the Q1 file begins with the four characters IMBL it will be treated as an imbalance patch Associated COVAL commands are necessary in order to indicate the variables for which imbalances must be computed but the values of CO and VAL appearing in them are immaterial Core Library case 805 may serve as an example It concerns flow around a sphere Several imbalance patches enclose the object as may be seen here The extent to which they agree about the z direction

    Original URL path: http://www.cham.co.uk/phoenics/d_polis/d_enc/imbal.htm (2016-02-15)
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  • s124
    2 0 3 1 0 GROUP 5 Z direction grid specification NREGZ 3 ZWLAST 1 0 IREGZ 1 GRDPWR Z unit 0 1 1 0 diminish z direction sizes 10 fold IREGZ 2 GRDPWR Z unit 2 0 01 1 0 IREGZ 3 GRDPWR Z unit 0 1 1 0 GROUP 7 Variables stored solved named Solve for P1 V1 W1 and TEM1 by whole field method SOLVE P1 V1 W1 TEM1 SOLUTN P1 Y Y Y N N N SOLUTN V1 Y Y Y P P P SOLUTN W1 Y Y Y P P P SOLUTN TEM1 Y Y Y N N Y Store other variables STORE PRPS DILA DVO1 DRH1 STORE EPSY STRY EPSZ STRZ EPST STRA T activate calculation of stress and strain in solid GROUP 8 Terms in differential equations devices TERMS TEM1 N Y Y Y Y Y CONVAC T use the vorticity method as convergence accelerator GROUP 9 Properties of the medium or media set via prps values TEXT Choose Fluid Materials 71 start of fluidmat store prps integer air20 airisent airideal water20 mercury freon integer 3gasideal stm100 stmisent stmideal air20 0 airisent 1 airideal 2 3gasideal 30 stm100 23 stmisent 24 stmideal 25 water20 67 mercury 66 freon 64 71 end of fluidmat LOAD 71 from the PHOENICS Input Library LOAD 71 from the PHOENICS Input Library TEXT Choose Solid Materials 70 start of solidmat store prps The following settings correspond to the IMAT ie PRPS values Note that only the first 6 characters of the names of the integers are significant integer alumin copper epoxy fibregl steel glass phase1 phase2 alumin 100 copper 103 epoxy 104 fibregl 105 steel 111 glass 106 70 end of solidmat LOAD 70 from the PHOENICS Input Library LOAD 70 from the PHOENICS Input Library GROUP 11 Initialization of fields of variables porosities etc working fluid is air FIINIT PRPS air20 Initialize Temperature and density to air density Field FIINIT TEM1 TIN Body properties are those of steel PATCH BODY INIVAL 1 NX 1 IYNORT IZLOW IZHI 1 1 INIT BODY PRPS 0 0 steel INIT BODY TEM1 0 0 TIN GROUP 13 Boundary conditions and special sources PATCH INLET LOW 1 NX 1 IYNORT 1 1 1 LSTEP COVAL INLET P1 FIXFLU 1 189 WIN COVAL INLET W1 ONLYMS WIN COVAL INLET TEM1 ONLYMS TIN outlet boundary condition name EXIT at NORTH or HIGH PATCH EXIT HIGH 1 NX 1 NY NZ NZ 1 LSTEP COVAL EXIT P1 1 0 0 0 COVAL EXIT TEM1 ONLYMS SAME porous medium resistances in parts of domain accessible to fluid PATCH PORMED1 PHASEM 1 1 1 NY 1 1 IZLOW 1 1 LSTEP COVAL PORMED1 V1 RESCO 0 0 PATCH PORMED15 PHASEM 1 1 IYNORT 1 NY 1 IZLOW IZHI 1 LSTEP COVAL PORMED15 V1 RESCO 0 0 PATCH PORMED2 PHASEM 1 1 1 NY 1 IZHI 1 NZ 1 LSTEP COVAL PORMED2 V1 RESCO 0 0 PATCH PORMED3 PHASEM 1 1 1 NY 1 IZLOW 2 1 LSTEP

    Original URL path: http://www.cham.co.uk/phoenics/d_polis/d_chron/ph36/bentbeam.htm (2016-02-15)
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