Time step calculation
 

Dear all How can we calculate the time stem for a case involving both convection, diffusion buoyancy and combustion. Thank you

Re: Time step calculation
 

Physically, determining the dominant process, for example,

convection -> delta_t approx delta_x / Vel diffusion -> delta_t approx delta_x deltaX / (2 diffCoef.) ...

and so on, the smallest delta_t is which your need to use.

Mathematically, you can use stability analysis, e.g, Matrix method or Von Neumann's, but it much more difficult depending on the problem.