Discrepancy between steady and transient calculations

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 May 14, 2010, 06:03 Discrepancy between steady and transient calculations #1 New Member   Pavel Join Date: May 2010 Posts: 1 Rep Power: 0 Hello I have a relatively simple task with Laval nozzle: v,1,0,0,0 v,2,0,3.319,0 v,3,1,0,0 v,4,0.718,0.991,0 v,5,0.704,1.198,0 v,6,1,3.319,0 vfill 4 5 5 10 1 ctab,4,shell,,,,,,,,off,,light ctname,4, ctab,4,shell,5,0,1,1,0,1,0,off,0,light ctname,4, csys,1 patch 1 3 6 2 15 100,,,,,,,,,0.85,1 2d3d,axisymmetric view 0 -1 0 rdef,3,inlet bzon,3,all (or pick 15 cells) view 0 1 0 rdef,4,outlet bzon,4,all (or pick 15 cells) pmat,1,fluid,AIR dens,ideal,y,28.96 lvis,suther,1.716e-05,116 spec,constant,1006 cond,constant,0.02637 pmat,1,fluid turb,ke,1,stan lowre,off coke,0.09,1.44,1.92,1.44,-0.33,0.419,1,1.219,0.9,,, pmat,1,fluid temp,on,thermal,total, etc... Boundary conditions: inlet V=10, dens=1.205,T=293 and I solve this task in two modes: Steady and transient (with timestep 1e-4, 100000 steps) But: In steady solution i have a correct decision In transient i have uncorrect decision: fluid accelerates along the length of the nozzle; besides, the flux sum on inlet and outlet do not match Can you explain the problem? Last edited by Dermer; May 14, 2010 at 07:58.

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