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Singular matrix error in CFD model for settling pond
Posted 2012/02/29 9:55 GMT-5 Computational Fluid Dynamics (CFD) Version 4.2a 1 Reply
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Hello,
I am trying to model the settling of solids in a settling pond with a mixture model.
The original model was 3D and the pond is a large structure and when we got the error we were unable to pin down exactly where the issue so we decided to down size and try a simple 1mx1m tank in 2D. I am still getting the same error.
The error reads singular matrix, "xyz" void equations...(the coordinates near the inlet and outlets).
It looks like a simple straight forward model... not sure what is causing teh problem.
Any help would be greatly appreciated!
Thanks,
Preethi
ps: unable to attach the model (file extension error!)... so ill try and provide as many details as possible.
The original 3D pond model:
parameters defined in the global definitions sections:
u_in 0.725m/s
phid_in 0.015
Geometry is a hexahedron with
upper surface LXB= 130X40
lower surface LXB= 90X2.4
Depth =8m
two inlet pipes 0.6m in dia, 4m in length at approx 0.6m depth from top and one outlet pipe (same dimensions as inlet pipes) at same hieght
mixture properties:
continuous phase: rho-1000kg/m3, viscocity 0.001pa.s
solid dispersed phase- rho 1600kg/m3, dia 6e-2
Boundary conditions: wall function at all boundaries except inlet/outlet
Inlets: Vel in x direction- u_in, specific turbulent length and intensity (default values), dispersed phase concentration - phid_in
Outlet: pressure no viscous stress p0=0, No dispersed phase flux (although tried a couple of other options like dispersed phase outlet & dispersed phase conce. with no useful result- leads to same resuls)
Gravity : -9.82 (also tried -gconst) in z direction
Initial conditions: all zeros. (although tried adding different numeral values values ( and phid_init and u_init and specifying in parameters) for u_in and phid_in )
Mesh: Two Tethed meshes, finer one for the corners and the inlet and outlet areas and slightly coarser one for the general body of pond
Solver: Stationary solver (default settings) : seggregated solver
I am trying to model the settling of solids in a settling pond with a mixture model.
The original model was 3D and the pond is a large structure and when we got the error we were unable to pin down exactly where the issue so we decided to down size and try a simple 1mx1m tank in 2D. I am still getting the same error.
The error reads singular matrix, "xyz" void equations...(the coordinates near the inlet and outlets).
It looks like a simple straight forward model... not sure what is causing teh problem.
Any help would be greatly appreciated!
Thanks,
Preethi
ps: unable to attach the model (file extension error!)... so ill try and provide as many details as possible.
The original 3D pond model:
parameters defined in the global definitions sections:
u_in 0.725m/s
phid_in 0.015
Geometry is a hexahedron with
upper surface LXB= 130X40
lower surface LXB= 90X2.4
Depth =8m
two inlet pipes 0.6m in dia, 4m in length at approx 0.6m depth from top and one outlet pipe (same dimensions as inlet pipes) at same hieght
mixture properties:
continuous phase: rho-1000kg/m3, viscocity 0.001pa.s
solid dispersed phase- rho 1600kg/m3, dia 6e-2
Boundary conditions: wall function at all boundaries except inlet/outlet
Inlets: Vel in x direction- u_in, specific turbulent length and intensity (default values), dispersed phase concentration - phid_in
Outlet: pressure no viscous stress p0=0, No dispersed phase flux (although tried a couple of other options like dispersed phase outlet & dispersed phase conce. with no useful result- leads to same resuls)
Gravity : -9.82 (also tried -gconst) in z direction
Initial conditions: all zeros. (although tried adding different numeral values values ( and phid_init and u_init and specifying in parameters) for u_in and phid_in )
Mesh: Two Tethed meshes, finer one for the corners and the inlet and outlet areas and slightly coarser one for the general body of pond
Solver: Stationary solver (default settings) : seggregated solver
1 Reply Last Post 2012/02/29 13:05 GMT-5