[srinath]

Hello

I find the line
fluxrequired
{
p
}
found in many system/fvSchemes, quite puzzling. What does this mean?
Does it mean p is required on the boundaries?

[schmidt_d]

Srinath,

If the code is solving a transport equation, it also calculates the fluxes at each cell face. If this information is useful to you after the solution of the equation, then you add it to the fluxrequired list in fvSchemes.

The pressure equation has div(grad(p)). So the flux here is a gradient of p that is located at the faces. This is quite different than the gradient of pressure at cell centers, that you would get with the normal fvc::grad(p). The gradient at p from the faces is very useful for updating fluxes.
-DPS