alaa_1973 wrote

hello dear

when i need the derivative of u or w in the t (the time) i,e ut or wt and put it in box of constant for equation step for navier-stokes to find the rho or mu the program tell me dont know (wt) which mean derivative of w for the time why and how i can solve this equation with my greeting

The syntax for equation specifications tries to as close as possible look like how one would write a partial differential equation with pen and paper. If for example the dependent variable is

**u** like in the example above, then

**u'** corresponds to the time derivative (the dependent variable followed by a single quote) ...

https://www.featool.com/doc/physics.html#phys_ceNote that the time dependent term is only used to assemble the mass matrix when using a time-dependent solver, and

**can not** be used as a equation, boundary, or postprocessing coefficient.