I'm using the method of manufacturated solution (MMS) to verify a cfd code (Transient energy equations).The equations are discretised with an implicit scheme and allow large time step without any problem, the concern is when I add the source term of the Manufacturated Solution, I only have convergence with small time steps.I don't know if there is any restriction condition about time step when using the MMS in a transient problem?!ps: my manufacturated solution is smooth and contains trigonometric and exponential functions.thanks in advance:)
Transient manufacturated solution
fluid dynamics