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Singular matrix error
Posted 26 mar 2013, 05:04 GMT-4 4 Replies
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Hi,
I am new to Comsol. I have been trying to simulate flow over NACA4412 airfoil. I have been using circular domain.
My boundary conditions are 1. no slip on the airfoil surfaces 2. inlet velocity - 25 m/s and 3. outlet .
Every time I try to compute it says Singular matrix error, there are equations giving Nan/Inf in the matrix rows.I have attached the mph file.
Please help.
Thanks
I am new to Comsol. I have been trying to simulate flow over NACA4412 airfoil. I have been using circular domain.
My boundary conditions are 1. no slip on the airfoil surfaces 2. inlet velocity - 25 m/s and 3. outlet .
Every time I try to compute it says Singular matrix error, there are equations giving Nan/Inf in the matrix rows.I have attached the mph file.
Please help.
Thanks
Attachments:
4 Replies Last Post 26 mar 2013, 12:54 GMT-4
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Posted:
1 decade ago
Hi
use rather a rectangle around your foil and 5-10x the size is enough, then inlet to the left, outlet to the right, and use "symmetry BC" for the upper and lower walls, or use open boundaries
Not sure what is wrong, I needed to remove your SPF physics and reload and redefine it, in my 4.3a to get it to solve, I can then use the default physics controlled mesh, while in your original model that one failed (no boundary mesh)
--
Good luck
Ivar
use rather a rectangle around your foil and 5-10x the size is enough, then inlet to the left, outlet to the right, and use "symmetry BC" for the upper and lower walls, or use open boundaries
Not sure what is wrong, I needed to remove your SPF physics and reload and redefine it, in my 4.3a to get it to solve, I can then use the default physics controlled mesh, while in your original model that one failed (no boundary mesh)
--
Good luck
Ivar
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Posted:
1 decade ago
I have tried with rectangular domain also. Every time I use the no- slip boundary conditon I get the same singular matrix error.
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Posted:
1 decade ago
As per your suggestion I have tried rectangular domain also. I have attached the mph file. Please have a look at it and give your valuable inputs.
Attachments:
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Posted:
1 decade ago
Hi
first do not set the air foil as symmetry, only the upper and lower box boundaries
Then do not start off with 25m/s vind velocity, your pressure and initial conditions has not managed to build up, use rather a parametric sweep to ramp up the speed.
Then is your fluid "incompressible" or compressible ? it solves partially for a slow speed and a rather coarse mesh but you seem to get some turbulences even at slow speed, that can give issues for the solver, CFD needs careful tweaking and some test and tries, it's not just "punch-off" at click ready ;)
--
Good luck
Ivar
first do not set the air foil as symmetry, only the upper and lower box boundaries
Then do not start off with 25m/s vind velocity, your pressure and initial conditions has not managed to build up, use rather a parametric sweep to ramp up the speed.
Then is your fluid "incompressible" or compressible ? it solves partially for a slow speed and a rather coarse mesh but you seem to get some turbulences even at slow speed, that can give issues for the solver, CFD needs careful tweaking and some test and tries, it's not just "punch-off" at click ready ;)
--
Good luck
Ivar