[nnprashant]

Hallo,

I am trying to simulate a model with massflow inlet (2 inlets) and a single static pressure outlet. Saying that I need to have an absolute total pressure at my inlet of 1.0 bar. I have achieved it by monitoring the total pressure at inlet and then decreasing my relative static pressure at outlet.

Instead of doing it manually, is it possible to write a CEL using so that it monitors the total pressure at inlet and thereby reduces the static pressure at outlet by an user-defined factor say for every 50 Iterations.

Any help would be much appreciated.

[JuPa]

Yes I think you can do what you want using simple CEL expressions.

There is an example in the CFX reference guide which uses variable inlet Temperature (and not mass flow rate). In your case replace temperature with mass flow rate since the theory is the same.

In the reference guide it's located in:

14.3.2. Example: Feedback to Control Inlet Temperature

[nnprashant]

Hallo RicochetJ

Thanks for the info. I have gone through the example, but the value of temperature is a step function which fluctuates between two values. In my case, to have a desired total pressure at inlet, i do not have a limit (say lower) limit for my static pressure. I do not know before hand for what value of static pressure would i get a absolute total pressure of 1 bar at inlet.

Is it possible to write a If loop for example,

if(massFlowAve(Total Pressure)@Inlet ==1.0[bar],DoNotChangeStaticPressure,ChangemyStaticPressureb ya Factor)

[PeMo]

Maybe you can try:

statOut=areaAve(Pressure)@Outlet
staticPressOut=if(massFlowAve(Total Pressure)@Inlet <1.0[bar],statOut,factor1*statOut)
where factor1<1
This works only if your coming from a high pressure. When you want to regulate from both sides (as you intended with ==1bar) you have to use sth like:

staticPressOut=if(massFlowAve(Total Pressure)@Inlet ==1.0[bar],statOut,changepressure)
changePressure=if(massFlowAve(Total Pressure)@Inlet >1.0[bar], factor1*statOut, factor2*statOut)
where factor1<1 and factor2>1
But in this case it is probably getting unstable since you never reach exactly 1bar.
(Not tested, just a guess)

[JuPa]

I just realised something...

If you want 1.0 bar at the outlet, and you don't know what to have on the inlet then just simply do this:

Set the outlet as a pressure outlet with a pressure of -1.0 bar

Set the inlets as openings with a pressure of 0 bar.

The solver will automatically determine the mass flow rates and pressures needed at the opening to maintain continuity.