Question

Which of these may cause a problem to implicit schemes?

(a) Coupled equations

(b) Partial differential equations

(c) Non-linear equations

(d) Linear equations

I had been asked this question in a national level competition.

This interesting question is from Explicit and Implicit Finite Difference Methods in portion Finite Difference Methods of Computational Fluid Dynamics

Answer 1

Correct option is (c) Non-linear equations

To explain: Though the implicit scheme has a great advantage of larger time steps, each step in an implicit scheme is large and takes more computational time. If the equation is non-linear, solving the system simultaneously will become more difficult. Usually, for these cases, the equations are linearized.