CAPE Forum

Ansys => Fluent => Topic started by: pitney1 on May 11, 2012, 10:54:13 AM

Title: How to enable Pressure work in Fluent
Post by: pitney1 on May 11, 2012, 10:54:13 AM

Hi,

I want to enable pressure work in fluent simulation. Can any one tell me how I can do that in Fluent?


Thanks.

Title: Re: How to enable Pressure work in Fluent
Post by: william on May 11, 2012, 10:57:36 AM

When Viscous heating is turned on, Pressure work must also be turned on. We know h = u + P/rho. where h = specific enthalpy; u = specific internal energy; P = pressure; rho = density.Hence delta(h) = delta(u) + delta (p/rho) = delta (u) + P.delta(1/rho) + (1/rho).delta(P).
For incompressible liquids with constant density , P.delta(1/rho) = 0 but we need to account for (1/rho).delta(P). For gases both incompressible and compressible, depending upon whether it is constant volume or constant pressure process, the appropriate pressure work remains.

When viscous heating is turned on, the increase in enthalpy needs to be accounted for by the pressure work term. Otherwise, you will see a fictitious drop in exit temperature to satisfy the enthalpy balance.

Here is how you turn on Pressure Work?

In the text interface Define->Models->Energy; FLUENT will prompt you for inclusion of viscous dissipation term, pressure work term, kinetic energy term.