[Ryanrwill]

Hi all,

I am trying to simulate a situation where air is forced into and out of a domain at a certain flow rate. Inside the domain there are two other pipes that are freely open to the atmosphere. There is also a porous zone between the two and blocking the main channel. As the porous zone porosity is reduced more air is forced to leave through the first pipe, causing more air to be pulled into the domain through the second to make up the outlet mass flow rate.

I currently have the simulation set up with velocity inlets for the inlet and outlet, with the outlet being a negative value, and pressure inlet and pressure outlet for the 2 pipes to free atmosphere.

However I am having trouble with residuals not dropping very far and being oscillatory.

Can anyone advise on how to set up this type of simulation please?

The attached diagram shows the current setup.

Thanks.

[NickFL]

Which software are you using, Fluent or CFX?



If you plot the residuals, where are the highest values? What does your mesh look like? Do you have adequate resolution? To simply says the residuals don't converge is not enough. There is potentially many problems that could exist.