LIQUID_FLOW: Replace darcy_gravity by specific_body_force
LIQUID_FLOW process takes the gravity into account via setting a positive scalar. Thereby it is assumed that gravity acts in the opposite direction of the one of the coordinate axes.
In line with the other processes the definition of a signed body force should be preferred instead.
<darcy_gravity> <!-- axis_id: 0, 1, 2 --> <axis_id> 0 </axis_id> <!-- g>=0. g=0: no gravity --> <g>9.81</g> <!--m/s²--> </darcy_gravity>
However, many examples then need to be adapted (automatically). Maybe it's worth it.