CFD Online Discussion Forums - Problems with Meshing: Collapsed Cells

Hi,

I'm having a problem with meshing in STAR-Cd, v3.26. I'm modeling a 20deg. wedge of a cylinder that has a spherical end. the cylindrical portion of the mesh seems to be fine. But the far end (where z is greater than 25), which is made in local spherical coordinates, is giving me the problem of collapsed faces (when phi=90). I recognize that this occurs because the cells faces that make up phi=90 meet on the axis and are effectively no longer faces, but edges. is there a way to fix this?

--Thank you for any help you can offer, the .inp file below can be read into Pro-STAR to make the geometry that gives me problems...

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!! ! This file sets up a wedge portion of the fuel cell !!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!! !!! This file sets up the domain, material properties. Does not !!! !!! setup the boundaries, as they are dependent on mouse clicks. !!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!

!Open STAR GUIde OPANEL TOOL EASY

!changing the memory restrictions for vertices,cells, memory maxvrt 5000000 memory maxcel 2000000

!Enable UDFs system ufiles

view,0,0,1 $angle,0 $replot rota,z,75 $replot rota,y,60 $replot

!Porosity indices are added in the cell table editor, radiation is off...

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !Defining Boundaries !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

rdef,1,inle $ $ $ $ $ $ $ $ $ $ rnam,1,Anode_In rdef,2,outl $ $ $ $ $ $ $ $ $ $ rnam,2,Anode_Out rdef,3,wall $ $ $ $ $ $ $ $ $ $ rnam,3,Cell_Wall

rdef,7,inle $ $ $ $ $ $ $ $ $ $ rnam,7,Cathode_In rdef,8,outl $ $ $ $ $ $ $ $ $ $ rnam,8,Cathode_Out

!Spherical Cyclics rdef,12,cycl $ $ $ $ $ $ $ $ $ $ rnam,12,Cyclic1 rdef,13,cycl $ $ $ $ $ $ $ $ $ $ rnam,13,Cyclic2

!Cylindrical Cyclics rdef,14,cycl $ $ $ $ $ $ $ $ $ $ rnam,14,Cyclic1 rdef,15,cycl $ $ $ $ $ $ $ $ $ $ rnam,15,Cyclic2

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !Creating Grid !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

!Set Cylindrical Coordinate System csys,2

!Creating Anode_Channel ctab,1,fluid,2,0,1,1,0,1,0,off,0 ctname,1,Anode_Channel vc3d,0,0.1,2,0,20,2,2,5,20 vc3d,0.1,0.9,16,0,20,2,2,5,20

!vc3d,0.1,0.2,1,0,30,1,2,5,20 !vc3d,0.2,0.3,1,0,30,2,2,5,20 !vc3d,0.3,0.9,6,0,30,5,2,5,20

vc3d,0,0.1,3,0,20,2,5,25,100 vc3d,0.1,0.9,16,0,20,2,5,25,100

!vc3d,0.1,0.2,1,0,30,1,5,25,100 !vc3d,0.2,0.3,1,0,30,2,5,25,100 !vc3d,0.3,0.9,6,0,9,3,5,25,100

!Creating Anode_Inactive ctab,3,fluid,3,1,1,1,0,1,0,off,0 ctname,3,Anode_Inactive vc3d,0.9,1.175,10,0,20,2,5,25,100

!Creating Anode_Active ctab,4,fluid,4,2,1,1,0,1,0,off,0 ctname,4,Anode_Active vc3d,1.175,1.185,1,0,20,2,5,25,100

!Creating Electrolyte ctab,7,solid,40,0,3,1,0,1,0,off,0 ctname,7,Electrolyte vc3d,1.185,1.1915,1,0,20,2,5,25,100

!Creating Cathode_Active ctab,5,fluid,5,3,2,1,0,1,0,off,0 ctname,5,Cathode_Active vc3d,1.1915,1.2065,1,0,20,2,5,25,100

!Creating Cathode_Inactive ctab,6,fluid,6,4,2,1,0,1,0,off,0 ctname,6,Cathode_Inactive vc3d,1.2065,1.2515,3,0,20,2,5,25,100

!Creating Cathode_Channel ctab,2,fluid,2,0,2,1,0,1,0,off,0 ctname,2,Cathode_Channel vc3d,1.2515,2.0,10,0,20,2,2,5,20 vc3d,1.2515,2.0,10,0,20,2,5,25,100 !vc3d,1.2515,2.0,5,0,20,2,25,28,20

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!

!Creating Couples !couple set 2 !cpta,2,2,5,14,2,off !cptn,2,blunt_end

!Creating Spherical End of Cell CLOCAL 4 SPHE 0,0,25,0,0,0 !Creating Anode_Channel ctab,1,fluid,2,0,1,1,0,1,0,off,0

!vc3d,0,0.9,18,0,20,2,0,89,15

vc3d,0,0.0333333,1,0,20,1,0,90,2 !vc3d,0,0.0333333,1,0,20,1,85,90,2 vc3d,0.0333333,0.0666666,1,0,20,1,0,90,3 !vc3d,0.0333333,0.0666666,1,0,20,1,85,90,3 vc3d,0.0666666,0.1,1,0,20,1,0,90,4 !vc3d,0.0666666,0.1,1,0,20,1,85,90,4 vc3d,0.1,0.2,2,0,20,1,0,90,5 !vc3d,0.1,0.2,2,0,20,1,85,90,5 vc3d,0.2,0.3,2,0,20,1,0,90,6 !vc3d,0.2,0.3,2,0,20,1,85,90,6 vc3d,0.3,0.4,2,0,20,1,0,90,7 vc3d,0.4,0.5,2,0,20,1,0,90,9 vc3d,0.5,0.6,2,0,20,1,0,90,11 vc3d,0.6,0.7,2,0,20,1,0,90,13 vc3d,0.7,0.8,2,0,20,1,0,90,15 vc3d,0.8,0.9,2,0,20,2,0,90,15

!vc3d,0.1,0.9,8,0,20,2,0,90,9

!Creating Anode_Inactive ctab,3,fluid,3,1,1,1,0,1,0,off,0 vc3d,0.9,1.175,10,0,20,2,0,90,15

!Creating Anode_Active ctab,4,fluid,4,1,1,1,0,1,0,off,0 vc3d,1.175,1.185,1,0,20,2,0,90,15

!Creating Electrolyte ctab,7,solid,40,0,3,1,0,1,0,off,0 vc3d,1.185,1.1915,1,0,20,2,0,90,15

!Creating Cathode_Active ctab,5,fluid,5,3,2,1,0,1,0,off,0 vc3d,1.1915,1.2065,1,0,20,2,0,90,15

!Creating Cathode_Inactive ctab,6,fluid,6,4,2,1,0,1,0,off,0 vc3d,1.2065,1.2515,3,0,20,2,0,90,15

$cset all $plty,ehid $cplo !Creating Cathode_Channel ctab,2,fluid,2,0,2,1,0,1,0,off,0 vc3d,1.2515,2.0,10,0,20,2,0,90,15

!Refining cell at blunt end cset news gran 1.1,1.237,-15,40,-1,91,4 crefine,2,3,4,cset,0,0,merg,nocouple

!Adding a set of cells to separate the flow in the anode csys,2 cset news gran 0.34,0.41,-15,40,0,24.8,2 ctyp,7 ctyp,7 $cmod,cset

!Refinging cell throughout length cset news gran 1.1,1.237,-15,40,0,25,2 crefine,2,3,8,cset,0,0,merg,nocouple

!Refining around anode channel separator cset news gran 0.2,0.5,-15,40,0,24.0,2 cset dele gran 0.34,0.41,-15,40,0,24.0,2 crefine,4,1,1,cset,0,0,merg,nocouple

cset news gran 0,0.8,-15,40,24.0,25,2 crefine,2,1,1,cset,0,0,merg,nocouple

!Tidying up numbering scheme !Removing cracks in grid, i.e. deleting all double vertices. cset,all cplo batch on $vmerge,all,,0.0001,,,,,,,low,delete $batch off !haha

!Creating Couple Definition cpta,1,1,2,4,3,off cptn,1,cell

!Creating Couples across the cell cpcr,cset,1

!Tidying up the numbering system vcom all y ccom y vset all

cset all cplo