Question

Which of these methods is recommended for the source term treatment in general?

(a) Treat sinks explicitly and sources implicitly

(b) Treat sinks implicitly and sources explicitly

(c) Treat the source term explicitly

(d) Treat the source term implicitly

I got this question during a job interview.

The question is from Source Term Discretization in division Discretization of the Source Term & Relaxation of Computational Fluid Dynamics

Answer 1

Right choice is (b) Treat sinks implicitly and sources explicitly

Explanation: If the source term is properly treated, the robustness of the problem will increase. In general, it is better to treat the sinks (negative values) implicitly and the sources (positive values) explicitly.