GROUP 1. Run title and other preliminaries TEXT(LAM-BRE K-E TURB. FLOW IN U-DUCT :T214 TITLE DISPLAY This case concerns plane, 2d incompressible flow through a 180 degree turnaround duct. The flow exhibits large streamline curvature together with flow separation near the bend exit next to the inner surface of the duct. Calculations are made with the low-Re k-e model of Lam and Bremhorst. Consequently, the numerical integration is taken down to the wall. The calculations employ a non-uniform mesh of NY=60 and NZ=80, for which the solution is not as yet grid independent. The calculation may also be performed with the modified low-Re k-e model of Chen and Kim [1987,1990]. The fine-mesh calculation employs a relatively coarse non-uniform mesh of NY=60 by NZ=80 which concentrates grid cells close to the wall. About 2000 sweeps are required for a converged solution with this mesh. However, for speed of computation the calculation is performed on a coarse mesh of NY=20 by NZ=40. Consequently, the solution is unlikely to be of sufficient quality because most of the near-wall cells are located too far from the wall for laminar conditions to apply on KE and EP. PHOENICS will actually activate log-law wall functions for velocities if the near-wall point lies outside the viscous sublayer. For demonstration purposes the calculation is set up for 20 sweeps, but 200 sweeps are required for complete convergence. ENDDIS PHOTON USE p view x gr ou x 1 msg velocity vectors vec x 1 sh msg pressto continue pause vec off; redr msg contours of w velocity resolutes con w1 x 1 fi;0.1 msg press to continue pause con del; redr msg contours of turbulence energy con ke x 1 fi;0.1 msg Press and then to END pause ENDUSE GROUP 1. Run title BOOLEAN(FINEG,CHENKIM);FINEG=F;CHENKIM=F REAL(REYNO,WIN,TKEIN,EPSIN,WIDTH,LENGTH,YAXIS) REYNO=1.E5;WIDTH=.0381;WIN=26.25;YAXIS=1.5*WIDTH;LENGTH=3.5*WIDTH GROUP 6. Body-fitted coordinates or grid distortion BFC=T;NONORT=T;NX=1 IF(FINEG) THEN + NY=60;NZ=80 ELSE + NY=20;NZ=40 ENDIF GSET(D,NX,NY,NZ,1.0,WIDTH,LENGTH) GSET(P,A,0.0,0.0,LENGTH);GSET(P,B,0.0,WIDTH,LENGTH) GSET(P,C,1.0,0.0,LENGTH);GSET(P,D,1.0,WIDTH,LENGTH) GSET(L,LAB,A,B,NY,S2.0);GSET(L,LBD,B,D,NX,1.0) GSET(L,LCD,C,D,NY,S2.0);GSET(L,LCA,C,A,NX,1.0) GSET(F,FABCD,A,-,B,-,D,-,C,-) GSET(M,FABCD,+J+I,1,1,1,TRANS) IF(FINEG) THEN + GSET(C,K81,F,K1,+,0.0,0.0,0.0) + GSET(C,K81,F,K81,+,0.0,(YAXIS+0.5*WIDTH),0.0) ** k81-k51 cells in the outlet length + GSET(C,K51,F,K81,+,0.0,0.0,-LENGTH,INC,0.8) ** k51-k21 cells in the bend + GSET(C,K21,F,K51,RX,-3.14159,YAXIS,0.0,INC,1.0) ** k21-k1 cells in the inlet length + GSET(C,K1,F,K21,+,0.0,0.0,LENGTH,INC,1.2) ELSE + GSET(C,K41,F,K1,+,0.0,0.0,0.0) + GSET(C,K41,F,K41,+,0.0,(YAXIS+0.5*WIDTH),0.0) ** k41-k31 cells in the outlet length + GSET(C,K31,F,K41,+,0.0,0.0,-LENGTH,INC,0.8) ** k31-k11 cells in the bend + GSET(C,K11,F,K31,RX,-3.14159,YAXIS,0.0,INC,1.0) ** k11-k1 cells in the inlet length + GSET(C,K1,F,K11,+,0.0,0.0,LENGTH,INC,1.2) ENDIF ** Set wup=t to account better for the high curvature of the w resolute... WUP=T GROUP 7. Variables stored, solved & named SOLVE(P1,V1,W1);SOLUTN(P1,Y,Y,Y,N,N,N) IF(CHENKIM) THEN + TURMOD(KECHEN-LOWRE) ELSE + TURMOD(KEMODL-LOWRE) ENDIF STORE(ENUT,LEN1);KELIN=1 GROUP 8. Terms (in differential equations) & devices GROUP 9. Properties of the medium (or media) ENUL=WIN*WIDTH/REYNO GROUP 11. Initialization of variable or porosity fields FIINIT(P1)=1.E-10;FIINIT(W1)=WIN TKEIN=(0.05*WIN)**2;EPSIN=TKEIN**1.5*0.1643/(0.09*WIDTH) ** Initial values FIINIT(KE)=TKEIN;FIINIT(EP)=EPSIN GROUP 13. Boundary conditions and special sources INLET(BFCIN,LOW,#1,#1,#1,#NREGY,#1,#1,1,1) VALUE(BFCIN,P1,GRND1);VALUE(BFCIN,W1,GRND1) VALUE(BFCIN,WCRT,-WIN);VALUE(BFCIN,KE,TKEIN) VALUE(BFCIN,EP,EPSIN) * Transfer density for GXBFC subroutine BFCA=RHO1 PATCH(OUTLET,HIGH,#1,#1,#1,#NREGY,#NREGZ,#NREGZ,1,1) COVAL(OUTLET,P1,1.E4,0.0) COVAL(OUTLET,V1,ONLYMS,0.0);COVAL(OUTLET,W1,ONLYMS,0.0) ** N-wall WALL(WFNN,NORTH,1,NX,NY,NY,1,NZ,1,1) ** S2-wall WALL(WFNS,SOUTH,1,NX,1,1,1,NZ,1,1) GROUP 15. Termination of sweeps LSWEEP=20; REAL(MASIN,DTF);MASIN=WIDTH*WIN*RHO1 RESREF(P1)=1.E-12*MASIN RESREF(W1)=RESREF(P1)*WIN; RESREF(V1)=RESREF(W1) RESREF(KE)=RESREF(P1)*TKEIN; RESREF(EP)=RESREF(P1)*EPSIN GROUP 16. Termination of iterations LITER(P1)=10 GROUP 17. Under-relaxation devices RELAX(P1,LINRLX,0.5);DTF=ZWLAST/WIN/NZ IF(.NOT.FINEG) THEN + DTF=10.*DTF ENDIF RELAX(W1,FALSDT,DTF); RELAX(V1,FALSDT,DTF) RELAX(KE,FALSDT,DTF); RELAX(EP,FALSDT,DTF) GROUP 22. Spot-value print-out IYMON=2;IZMON=NZ/2;NPRMON=LSWEEP GROUP 23. Field print-out and plot control NPRINT=LSWEEP;ITABL=2;NPLT=10;NYPRIN=2;NZPRIN=10 TSTSWP=-1;YPLS=T