web-archive-uk.com


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".
  • enc_T341.HTM
    when the main flow direction is aligned with gravity and zero when the main flow direction is perpendicular to gravity The computed value of C3 can be stored by using the command STORE C3EB in the Q1 file If PHOENICS VR is not used then a default value of C3 1 0 is employed via the setting GCEB 1 0 in the GROUND subroutine GXKEGB in the file GXGENK FOR A value of C3 0 0 may be effected by simply not using a COVAL statement for EP The default value OF GCEB 1 0 may be overwritten by setting for example SPEDAT SET KEBUOY GCEB R 0 2 in the Q1 file The setting SPEDAT SET KEBUOY GCEB R 1 0 arranges that C3 is computed from equation 8 above The model presented above is applicable only in regions where the turbulence Reynolds number is high Near walls where the Reynolds number tends to zero the model requires the application of so called wall functions see Section 8 below or alternatively the introduction of a low Reynolds number extension see Sections 3 3 1 and 3 4 4 The standard model employs the wall function approach Performance of the model It should be mentioned that the standard form of the KE EP model has been found to perform less than satisfactorily in a number of flow situations including separated flows buoyancy streamline curvature swirl turbulence driven secondary motions rotation compressibility adverse pressure gradients and axi symmetrical jets Nevertheless because the model is so widely used variants and or ad hoc modifications aimed at improving its performance abound in the literature The most well known include a the RNG Chen Kim and Yap variants for use in separated flows and b the ad hoc Richardson number modification of Launder et al 1977 for curvature swirl and rotation 3 Activation of the model The standard KE EP is activated by inserting the PIL command TURMOD KEMODL in the Q1 file which is equivalent to SOLVE KE EP ENUT GRND3 EL1 GRND4 KELIN 0 PATCH KESOURCE PHASEM 1 NX 1 NY 1 NZ 1 LSTEP COVAL KESOURCE KE GRND4 GRND4 COVAL KESOURCE EP GRND4 GRND4 GENK T TERMS KE N Y Y Y Y N TERMS EP N Y Y Y Y N The sources for KE and EP are calculated and inserted in subroutine GXKESO called from GROUP 13 of GREX Different linearizations of these sources are selected by the KELIN parameter The generation rate used in the source terms can be stored by the command STORE GENK The WALL and CONPOR commands create the required wall function COVAL settings automatically COVAL WALLN KE GRND2 GRND2 COVAL WALLN EP GRND2 GRND2 or COVAL WALLN KE GRND3 GRND3 COVAL WALLN EP GRND3 GRND3 if the user sets WALLCO GRND3 in the Q1 file Thus the PHOENICS default is equilibrium GRND2 wall functions However in separated flows the use of non equilibrium GRND3 wall functions is recommended especially if wall heat transfer is

    Original URL path: http://www.cham.co.uk/phoenics/d_polis/d_enc/turmod/enc_t341.htm (2016-02-15)
    Open archived version from archive



  • Re damping functions and Pk is the volumetric production rate of KE The empirical constants The following constants are normally used PRT KE 2 0 PRT F 2 0 CMUCD 1 0 CD 0 09 C1F 5 9 C2F 3 40 The Damping functions The damping functions which are set to unity in the high Re model are defined by FMU 1 40 RT RK 1 RT RK 2 6 F1 1 FMU 0 1 RT RW 1 RT RW 2 7 F2 5 18 RT RB 4 1 RT RB 4 2 8 where RB 8 RK 6 0 RW 2 7 and RT is the turbulent Reynolds number RT K F ENUL 2 9 In regions where RT is high FMU F1 and F2 tend to unity 3 Boundary Conditions Wall boundary conditions At present the high Re KE F model is restricted to using equilibrium GRND2 wall functions so that the following boundary conditions are applied for the turbulence variables KE UTAU 2 SQRT CD F UTAU SQRT CD k Y 3 1 where UTAU is the resultant friction velocity SQRT TAUW RHO TAUW is the wall shear stress Y is the normal distance of the first grid point from the wall and k is von Karman s constant If the low Re version is selected then KE 0 at the wall and the following condition is applied for F at the near wall grid point F 2 ENUL C2F Y 2 3 2 The alternative condition of F 2 ENUL CD F2 Y 2 also proposed by Wilcox 1988 produces nearly identical results and so it has not been coded in PHOENICS Inlet conditions At mass inflow boundaries the inlet values of KE and F are usually unknown and one needs to take guidance from experimental data for similar flows The simplest practice is to assume uniform values of KE and F computed from KE I U 2 F EP CD KE EP 0 1643 KE 1 5 LM 3 3 where U is the bulk inlet velocity I is the turbulent intensity typically in the range 0 01 lt I lt 0 05 and the mixing length LM 0 1H where H is a characteristic inlet dimension say the hydraulic radius of the inlet pipe Free stream conditions At free entrainment boundaries where a fixed pressure condition is employed it is necessary to prescribe free stream values for KE and F If the ambient stream is assumed to be free of turbulence then KE and EP can be set to negligibly small values and F can then be calculated from equation 2 5 It should be mentioned that when using F 0 in the free stream the KE F model consistently predicts spreading rates of free shear layers that exceed measured values by more than 20 As was noted earlier and discussed by Wilcox 1993 these solutions are in fact quite sensitive to the free stream value of F Speziale et al 1990 and Menter

    Original URL path: http://www.cham.co.uk/phoenics/d_polis/d_enc/turmod/enc_t346.htm (2016-02-15)
    Open archived version from archive

  • ENC_T345.HTM
    were chiefly thought of at that time it was the direction of the vorticity which was thought of was that normal both to the main flow and to the plane in which it was confined However this assumption had no effect on the form of the equations b The effective viscosity presumption In accordance with the requirements of dimensional analysis then efective viscosity formula took the form EV const KE

    Original URL path: http://www.cham.co.uk/phoenics/d_polis/d_enc/turmod/enc_t345.htm (2016-02-15)
    Open archived version from archive


  • KEY.HTM
    point with A K For polygons C is used to mark subsequent points then O to close and fill A new fill colour must be loaded using P before starting the polygon definition See also HELP on KEY CLEAR KEY COLOUR KEY DELETE KEY MOVE KEY LIST KEY SIZE KEY REPLACE TEXT Key Photon Help Key toggles the display of the reference vector and the colour bar for vector size KEYCOLO Autoplot Help K EY CO LOUR i n Changes colour of line i from current colour to colour n The program will prompt for i and n if these are omitted See also HELP on KEY KEY CLEAR KEY DELETE KEY MOVE KEY LIST KEY REPLACE KEYKEEP Autoplot Help K EY K EEP Keys will not be cleared from memory by a CLEAR command but will be retained for the next plot GROUP associations will also be kept See also HELP on KEY GROUP KEYLIST Autoplot Help K EY L IST List the current line types See also HELP on KEY KEY CLEAR KEY COLOUR KEY DELETE KEY MOVE KEY REPLACE KEYMOVE Autoplot Help K EY M OVE i Moves i th line to the new position located by cursor C can be used to locate the cursor for repeated moves The program will prompt for i if required N can be used to request the next key to be moved If a polygon is to be moved then all its component keys should be GROUPed and the group moved as a whole Moving individual sides of a polygon is allowed Use the REDRAW command for a clean plot See also HELP on KEY KEY CLEAR KEY COLOUR KEY DELETE KEY LIST KEY REPLACE GROUP MAKE GROUP MOVE KEYREAD Autoplot Help K EY REA D Keys will be read

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

  • SATLIT.HTM
    their associated dimension indicating parameters is supplied in the table which concludes this sub section The fourth column of the table indicates the corresponding array that appears in the MAIN program of EARTH so that if it is re dimensioned in the MAIN program of the SATELLITE it must also be re dimensioned in the MAIN program of EARTH Once a change to the FORTRAN has been made the SATLIT file must be re compiled and the SATELLITE task re linked for the changes to have effect The same comment applies to any corresponding changes made to the MAIN program of EARTH Table Notes Arrays marked must have identical values in MAIN and SATLIT Where associated EARTH arrays exist the dimensions in MAIN of EARTH must exactly match those in MAIN of SATELLITE Array name Dimension parameter Associated EARTH array F NFDIM MAXTCV MAXFRC NBFC None RUN MAXRUN 500 None LG NLG 20 LG IG NIG 20 IG RG NRG 100 RG CG NCG 10 CG LSGD NLSG 20 LSGD ISGD NISG 20 ISGD RSGD NRSG 100 RSGD CSGD NCSG 10 CSGD INDEC NIPIL 45 None INVAL None REDEC NRPIL 45 None REVAL None STACK NSTACK 500 None DBGPHI NUMPHI 50 L5 ITERMS I1 LITER I2 I0RCVF I3 I0RCVL I4 ISLN I5 IPRN I6 NAME IH1 DTFALS R1 RESREF R2 PRNDTL R3 PRT R4 ENDIT R5 VARMIN R6 VARMAX R7 FIINIT R8 PHINT R9 CINT R10 EX R11 IP1 IP1 IHP2 IHP2 RVAL RVAL LVAL LVAL SATLIT The following account is intended to assist those PHOENICS users who wish to insert coding into SATLIT for example in order to read data from a file or to make one set of data items depend upon others in complex ways involving mathematical operations which PIL may not be able to handle as expeditiously as Fortran The listing of SATLIT can be viewed via POLIS PHOENICS 2 Fortran Study of the SATLIT listing reveals that it consists mainly of a series of 24 groups of statements beginning with a comment followed by a CONTINUE and one or more RETURNs Which group is activated during execution at any time is controlled by a computed GO TO just below the common blocks The titles of the groups are the same as those which are used in Q1 files and which recur in GROUND and related files No coding appears between the CONTINUEs and the RETURNs for SATLIT is provided as an empty shell into which the user can introduce whatever coding he desires The user should note the following important point SATLIT is always called during execution of the SATELLITE program after the Q1 file has been processed but before the interactive TALK T session starts The user can cause additional execution of the SATLIT either in Q1 or interactively by means of the command SATRUN NAMSAT This may be necessary when SATLIT coding makes reference to PIL variables Once the coding has been inserted it is the user s responsibility to arrange for compilation

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


  • 2 7 where Cs is the Smagorinsky constant 0 17 and H is a representative mesh interval The Smagorinsky constant Cs is known to vary with application with values reported in the literature ranging from 0 1 to 0 25 The default value in PHOENICS is 0 17 For the Smagorinsky WD Model LM MIN Cs H k WDIS 5 1 2 8 where k is von Karman s constant 0 41 and WDIS is the normal distance to the nearest wall calculated via the solution of an elliptic differential equation for the variable LTLS see the PHOENICS Encyclopaedia entry DISWAL According to Schumann 1991 the MIN operator makes the model valid for coarse grids in particular near walls where the mixing length k WDIS may become smaller than the mesh interval H The Smagorinsky VDWD model calculates LM from LM Cs H FMU 5 1 2 9 where FMU is the Van Driest 1956 damping function given by FMU 1 EXP Y 26 0 m n 5 1 2 10 The dimensional wall distance y is computed using the normal distance to the nearest wall WDIS The empirical exponents m and n are defaulted to unity in PHOENICS Equation 5 1 2 9 is an alternative to equation 5 1 2 8 for partially taking into account wall effects by appropriately reducing the length scale Cs H in the proximity of walls The Grid Filter Width H The representative mesh interval H is computed from H V 1 3 5 1 2 11 where V is the local cell volume An alternative commonly encountered in the literature is also provided as an option in PHOENICS H S DXi 2 N 1 N 5 1 2 12 where the summation is over the three coordinate directions and DXi is the cell width in the direction i The Subgrid Scale Heat Fluxes The SGS heat fluxes are modelled by Qj Kturb T j 5 1 2 13 where Kturb RHO ENUT Cp PRT TEM1 and PRT TEM1 is the subgrid Prandtl number which is the LES analog of the turbulent Prandtl number In the LES literature a broad range of values has been proposed for this parameter from 0 25 to 0 9 see for example Ciofalo 1994 5 1 3 Activation of the Model The default in PHOENICS is the Smagorinsky WD model which may be activated from the Q1 input file via the PIL command TURMOD SGSMOD which is equivalent to ENUT GRND2 EL1 GRND10 GENK T EL1A 0 17 EL1B 0 41 DISWAL Here EL1A equals Smagorinsky s constant and EL1B von Karman s constant The basic Smagorinsky model is activated by setting TURMOD SGSMOD EL1B 0 0 and if no walls are present by deactivating the PIL command DISWAL via SOLUTN LTLS N N N N N N and SOLUTN WDIS N N N N N N The Smagorinsky VDWD model is activated by setting TURMOD SGSMOD EL1B 0 0 EL1C 1 0 EL1D 1 0 where

    Original URL path: http://www.cham.co.uk/phoenics/d_polis/d_enc/turmod/enc_tu51.htm (2016-02-15)
    Open archived version from archive

  • LINK.HTM
    INTERVALS GRDPWR Y NY YLENGTH 1 0 GROUP 5 Z DIRECTION GRID SPECIFICATION DOMAIN IS ZLENGTH M LONG IN Z DIRECTION WITH EQUAL INTERVALS GRDPWR Z NZ ZLENGTH 1 0 GROUP 7 VARIABLES STORED SOLVED NAMED CHOOSE FIRST PHASE ENTHALPY H1 AS DEPENDENT VARIABLE AND ACTIVATE THE WHOLE FIELD ELLIPTIC SOLVER SOLUTN H1 Y Y Y N N N NAME H1 TEMP STORE VPOR SOLVE P1 U1 V1 SOLUTN P1 Y Y Y N N N STORE IMB1 PCOR GROUP 8 TERMS IN DIFFERENTIAL EQUATIONS DEVICES FOR PURE CONDUCTION CUT OUT BUILT IN SOURCE AND CONVECTION TERMS TERMS TEMP N N Y N Y Y GROUP 9 PROPERTIES OF THE MEDIUM OR MEDIA THERMAL CONDUCTIVITY WILL BE ENUL RHO1 PRNDTL TEMP SO ENUL 1 0E 3 RHO1 1 0 PRNDTL TEMP 1 0 GROUP 11 INITIALIZATION OF VARIABLE OR POROSITY FIELDS INIADD F IF L2R THEN FIINIT U1 0 5 ELSE FIINIT U1 0 5 ENDIF FIINIT VPOR 1 0 IF IYSHFT GT 0 THEN CONPOR BAR1 0 0 CELL NXNOM 2 1 NXNOM 2 1 1 IYSHFT 1 NZ CONPOR BAR2 0 0 CELL NXNOM 2 2 NXNOM 2 2 NY IYSHFT 1 NY 1 NZ ENDIF IF IYSHFT LT 0 THEN CONPOR BAR1 0 0 CELL NXNOM 2 1 NXNOM 2 1 NY 1 IYSHFT NY 1 NZ CONPOR BAR2 0 0 CELL NXNOM 2 2 NXNOM 2 2 1 IYSHFT 1 NZ ENDIF GROUP 13 BOUNDARY CONDITIONS AND SPECIAL SOURCES COLD BOUNDARY ON THE LEFT IF L2R THEN PATCH COLD WEST 1 1 IYBOT NY 1 1 1 1 COVAL COLD U1 ONLYMS 1 0 ELSE PATCH COLD WEST NX NX IYBOT NY 1 1 1 1 COVAL COLD U1 ONLYMS 1 0 ENDIF COVAL COLD TEMP 1 E5 0 9 COVAL COLD P1 FIXFLU 1 0 HOT BOUNDARY ON THE RIGHT IF L2R THEN PATCH HOT CELL NX NX 1 NY NZ NZ 1 1 ELSE PATCH HOT CELL 1 1 IYBOT NY 1 1 1 1 ENDIF COVAL HOT TEMP 1 E5 0 9 COVAL HOT P1 1 E 2 0 0 IYPLUS IS INTRODUCED IN AN ATTEMPT TO COUNTERACT THE EFFECT OF THERE BEING NO V CELLS AT THE SOUTH AND NORTH BOUNDARIES IYPLUS 0 IF IYSHFT GT 0 THEN IYPLUS 1 ENDIF IF IYSHFT LT 0 THEN IYPLUS 1 ENDIF IYPLUS IYPLUS IYPLUS 0 MESGM IYPLUS IYPLUS CORRECT IF IYSHFT GE 0 THEN PATCH 1 WEST NXNOM 2 1 NXNOM 2 1 1 IYSHFT NY 1 1 1 1 PATCH 1U WEST NXNOM 2 NXNOM 2 1 IYSHFT NY 1 1 1 1 ELSE PATCH 1 WEST NXNOM 2 1 NXNOM 2 1 1 NY IYSHFT 1 1 1 1 PATCH 1U WEST NXNOM 2 NXNOM 2 1 NY IYSHFT 1 1 1 1 ENDIF COVAL 1 TEMP 1 E5 ISHIFT COVAL 1 P1 P1CO ISHIFT COVAL 1 U1 FIXVAL ISHIFT COVAL 1 V1 FIXVAL ISHIFT IYPLUS COVAL 1U U1 FIXVAL ISHIFT INTEGER III III NXNOM 2 2 IF IYSHFT GE 0 THEN

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

  • LOGIC.HTM
    in PIL T or F signifying TRUE or FALSE respectively Declared logical variables eg LOG3 not LOG4 Expressions of the form numeric expression operator numeric expression In this case implicit FLOATing is performed on integer values ie the integer values are treated as real and all FORTRAN operators are valid ie all equalities and inequalities may be expressed eg NX GT NN and character expression operator character expression In this case a character variable enclosed by colons inserts the current value of that variable into an expression It should be noted that only the operators EQ and NE are valid in expressions of this type eg CC 4 5 AB EQ CC Simple logical expressions can be combined with the logical operators AND OR and NOT to create arbitrarily complex logical expressions There are two limitations to the use of logical operators firstly there is no precedence defined so that in the absence of brackets evaluation is carried out from left to right It is therefore recommended that brackets be used to remove potential ambiguity from complex logical expressions a NOT operator must not immediately follow an AND or OR without an intervening bracket Thus CARTES OR NOT NONORT is

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



  •  


web-archive-uk.com, 2017-12-18