Hello! I am a new user and just started learning MFiX. I understand what a time step size is. It is the division of time on which the maximum iterations we have given are going to perform. But, what is meant by minimum time step size? and maximum time step size?
MFiX uses an adaptive time step. When convergence is good (few iterations per time step), the time step increases so we can march faster. If convergence is slow or unphysical results are detected, the time step decreases. The min and max time steps bound the range of the time step. If we reach the minimum, then MFiX declares a solution cannot be found and quits. If the maximum time step is reached, then it won’t increase anymore even if convergence is good.