Question

Which of these is correct regarding implicit schemes?

(a) Truncation error is less

(b) Computation time is more

(c) Time-step size is small

(d) Easy to set-up

The question was asked during a job interview.

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

Answer 1

Correct choice is (a) Truncation error is less

Explanation: As the time-step size is very large, the truncation error may become large and the accuracy of results may be less when compared to that of the explicit schemes. The total time of computation is less. But the algorithm is difficult to set-up.