Finite Difference Time Steps?
Finite Difference Time Steps?
(OP)
I am using a finite-difference thermal solver to evaluate a transient heat-transfer problem. I have chosen an implicit forward/backward (i.e., central) differencing method. The problem is with the time step. If I choose a time step twice as large as the software calculates, I seem to get reasonable answers. If I choose a time step half as large, I get an unstable solution or at least one that seems to be nonsensical. This seems to fly in the face of theory. I always thought using a smaller time step resulted in a longer solution time, not an unstable solution. Does anyone have any experience with this? (My problem involves radiation to space and orbital heating.) Thanks in advance.





RE: Finite Difference Time Steps?
RE: Finite Difference Time Steps?
Conversely, due to the mathematical nature of finite-difference approximations, truncation or discretization errors can result if the time step is too large. So the trick is in minimizing the errors from both by choosing an appropriate time step. Unless you have a priori knowledge of what the solution should be, this "trick" becomes even trickier. I eventually was able to compare my results with another analysis and was then able to correct the mistake. Thanks again for your input.