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February 11, 2013, 09:32 
Unresolved problem and Queries

#21  
Member
Himanshu Sharma
Join Date: Jul 2012
Posts: 85
Rep Power: 6 
Quote:
From other post on the forums (http://www.cfdonline.com/Forums/ope...rintstack.html) i came across checking the mesh by "checkMesh" i did that thing and found few things about my mesh bold ones. Code:
Overall number of cells of each type: hexahedra: 223866 prisms: 0 wedges: 0 pyramids: 0 tet wedges: 0 tetrahedra: 0 polyhedra: 0 Checking topology... Boundary definition OK. Cell to face addressing OK. Point usage OK. Upper triangular ordering OK. Face vertices OK. Number of regions: 1 (OK). Checking patch topology for multiply connected surfaces ... Patch Faces Points Surface topology wall 21803 21858 ok (nonclosed singly connected) inlet 278 300 ok (nonclosed singly connected) outlet 493 528 ok (nonclosed singly connected) Checking geometry... Overall domain bounding box (0.0199212 4.33681e19 0.0008) (0.00992118 0.01 0.0108) Mesh (nonempty, nonwedge) directions (1 1 1) Mesh (nonempty) directions (1 1 1) Boundary openness (2.29843e15 2.69037e17 4.91973e18) OK. Max cell openness = 3.26926e16 OK. Max aspect ratio = 21.2719 OK. Minumum face area = 1.27927e10. Maximum face area = 1.16148e07. Face area magnitudes OK. Min volume = 1.28223e14. Max volume = 2.27969e11. Total volume = 1.00065e06. Cell volumes OK. Mesh nonorthogonality Max: 43.6834 average: 7.57081 Nonorthogonality check OK. Face pyramids OK. Max skewness = 1.12467 OK. Coupled point location match (average 0) OK. 

February 12, 2013, 09:08 

#22 
Member
Ali Khalifesoltani
Join Date: Mar 2011
Location: Esfahan, Iran
Posts: 52
Rep Power: 7 
Hi,
According to CFL condition, your dt should be less than 1.2e14 sec, so you should make a coarser mesh. I am not an expert on openFoam but as much as I know if you don't overconstrain the B.Cs there should be no problem in the boundary conditions you defined. I ran your case and worked a little bit on it but no success was observed. I thought that the problem is probably for your Initial Pressure Condition in the domain and it will cause some math. error in the solution but there was no success. I think the first step to solve your problem is to obey the CFL condition(by decreasing dt or making a coarser mesh) and then investigate on the B.Cs. Regards. Ali 

February 13, 2013, 00:43 

#23  
Member
Himanshu Sharma
Join Date: Jul 2012
Posts: 85
Rep Power: 6 
Quote:
Thanks for Reply I also think that it necessary for defining an interior pressure conditions in side the box since i don't think wit the given velocity inlet the solver is developing the interior pressure field. but then if i specify some interior pressure inside the domain then it will start affecting my inlet boundary conditions hence i am totally in a mess how to make this problem as this is on of my projects in the university.And i will now try to coarse my mesh and then try to implement the boundary condition how it might work.if you find some ways than please do share. Regards Himanshu sharma 

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