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Old   December 20, 2002, 11:41
Default piston cavities
  #1
Mihir Desai
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Hi,

Does anybody know how to model piston cavities(hemispherical bowl-in-piston,etc.) using STAR-CD,without using PROICE or SPEED.Any info in this regard will be really helpful.Thanx in advance

Mihir.
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Old   December 22, 2002, 23:51
Default Re: piston cavities
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CJ Tune
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If you have an hex automesher like Pro*AM, you can use it to mesh the combustion bowl and *just* one layer of cells above it, together. Build a layer of shells on top of that one layer of hex/trimmed/prism cells and then *delete* those cells. Now, you can just use VCEX based on that shell patch you just created, and later with VMER, hopefully you can get a nice one-to-one cell face correspondence betweem the Pro*AM generated combustion bowl mesh and that ProSTAR 'hand-built' moving mesh layer. Use REST to get your vertex numbering correct, if need be. No automesher? Guess you are stuck with just ProSTAR's traditional block-meshing. Try drawing the guiding lines (as frames for the mesh blocks) in your CAD program -easier with freeform 3D CAD.
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Old   December 23, 2002, 03:59
Default Re: piston cavities
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Mihir Desai
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Hi,

Thanx a lot for replying.I've built the combustion bowl mesh and the layer above it using GAMBIT.I also have a one-to-one correspondence b/w these cells and the prostar mesh.But my problem pertains to moving this set.I've tried using Arbitary Sliding Interface Method to match the bowl cells with the prostar cells.This works fine during the exhaust stroke,when the piston is moving up.But as soon as the first cell layer is reactivated during the intake stroke,this match breaks down and the solution stops.Is the ASI approach correct for this sort of a problem?Or is there some other methodology?

Thanx again

Mihir.
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Old   December 23, 2002, 10:15
Default Re: piston cavities
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CJ Tune
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ASI? Betweem the combustion bowl cell set and the collapsing/expanding ProSTAR cell set? We are talking about the piston movement only, right? I cannot imagine the need for any sliding interfaces in your model -are you doing a 2-stroke where the exhause and intake ports are to the sides? or are you referring to ARBITRARY CELL COUPLES? That is not the same as ARBITRARY SLIDING INTERFACE. I don't think you can deactivate any cell layers that has couples. If you have a 1-to-1 CELL FACE correspondence between the combustion bowl cells and the ProSTAR 'accordion' cell set, then you should have no need of any couples.
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