Warning: Singular matrix detected when solving for : T_s

Hello everyone

I am getting "Warning: Singular matrix detected when solving for : T_s" as warning. Can someone tell me what could be causing this and how can I solved it? Also may I know what it meant by Singular matrix? Any advice you can provide would be greatly appreciated.

Thank you in advance.
gasifier_0.3_60sec_2022-06-13T160150.877477.zip (36.4 KB)

“Singular matrix” means that a system of linear equations cannot be solved because the matrix of coefficients cannot be inverted.

How long did the simulation run before this error appeared?

I got past this error by changing from “Superbee” to “First-order upwind” for the energy equation. You might also experiment with the relaxation factors.

Thank you @cgw for your valuable suggestion. Today, I have changed energy equation to first order upwind method and restarted the simulation. Now, its working fine and I have not encountered with any error.