I wrote codes below to simulate the flow over an circular cylinder. But the Cd was not exact to 0.6 for Re=1e7. Can you teach me what are errors, how can I improve the results. Thanks. ( johnny@vol.vnn.vn)

CODES: !Re = 3.09e-6 !air density = 1.23 !Velocity = 45 !Diameter = 1 !Vicousity coeifficient = 1.789e-5 !divisions of 1/4 circle = 64 !rectangle-wind tunnel size is 150x100 /unit,si /prep7 rectng,0,150,0,100 local,11,0,75,50,0,,,,1,1 csys,11 wpcsys,-1 pcirc,0.5,0,0,360 aovlap,all adel,2 !circle is deleted lsel,s,,,1,3,2 lesize,all,3,,,1 lsel,s,,,2,4,2 lesize,all,2,,,1 lsel,s,,,5,8 lesize,all,,,64,,1 allsel et,1,141 !mshape,0 !try triangle mesh amesh,all dl,4,,vx,45,0 !line 4, inlet, Vx = 45, Vy = 0 dl,4,,vy,0,0 vv dl,2,,pres,0,0 !outlet, P=0 dl,1,,vx,0,1 !line 1 - bottom dl,1,,vy,0,1 dl,3,,vx,0,1 !line3 - top line dl,3,,vy,0,1 dl,5,,vx,0,1 !lines on circle, dl,5,,vy,0,1 dl,6,,vx,0,1 dl,6,,vy,0,1 dl,7,,vx,0,1 dl,7,,vy,0,1 dl,8,,vx,0,1 dl,8,,vy,0,1

/solu FLDATA5,OUTP,PCOE,1 !add a pressure coefficient DOF fldata1,solu,turb,1 !turbular solution flda,iter,exec,1000 FLDATA3,TERM,PRES,1e-004 FLDATA3,TERM,TEMP,1e-004 flda,prot,visc,constant !fluid property, constant flda,prot,dens,constant fldata,nomi,dens,1.23 fldata,nomi,visc,1.789e-5 allsel solve FINISH /POST1 SET,LAST PLNSOL,PCOE,,0, lsel,s,,,5,8 nsll,s,1 INTSRF,PRES

I assume this is a ANSYS Flotran?

CODES: !Re = 3.09e-6

Hopefully, this is a typo! you should have 3.09e6. As for the rest, you are not "writing" a code as you claim, but just inputting data. As such, it is difficult to answer your general question without knowing the details.

Adrin Gharakhani