[dhehdxhdaus]

Hello dear everyone, thank you for your help as always.
I'm not good at English or programming, so I'm sorry that I always seem to make basic mistakes.



To briefly explain the shape I want to experiment with, two inlets and two outlets exist simultaneously in one fluid flow.
Here, there is an inlet called A and an inlet called B, and an outlet called A' and an outlet called B'.

Here, it is ideal that all of the flow coming in from A goes out to A', and the flow going out of B and going out to B' will interfere with this flow.

I have two questions here.

1. If two inlets are involved in the flow out of both outlet, is there a way to quantitatively check what percentage of the flow from specific outlet is occupied by the flow rate from each inlet?
From this, we want to see how ideal the flow was.


2. When the flow of the two inlets and the two outlets has a slightly complicated shape, is it possible to calculate the degree of flow that enters from the inlet but does not go out through the outlet and is isolated in the pipe over time?



The analysis is running at both steady and transient and the fluid is water. Thank you for your help as always.

[Gert-Jan]

make 1 inlet 20 degC and the other 30 degC. The average T on the outlets will give an indication of mixing

[evcelica]

1.) Use two "additional variables" in your fluid. (Actually you could probably use just 1, but lets go with 2)
These are passive scalars in the fluid. Set Inlet A to have some arbitrary value of scalar A, with zero B, and Inlet B to have an arbitrary value of scaler B, with zero A. Check the massflowAve of each of those scalars at the two outlets.
2.) Everything that goes in will go out, conservation of mass. it can't accumulate in the pipe. If you are looking for residence time or dead zones, you can use a third scalar C. With that use a subdomain over the whole volume and apply a volumetric source of 1 Scalar C value per second, and results will show you the average residence time for that volume.
The Time variable on streamlines may also be useful, and can help visualize #1.

Gert-Jan's approach will work as well, beat me to it.
But only if you don't need to actually calculate temperatures for other reasons, which you likely don't in your case.

[dhehdxhdaus]

Originally Posted by Gert-Jan

make 1 inlet 20 degC and the other 30 degC. The average T on the outlets will give an indication of mixing

It's an easy way for me to use it, too. Thank you!

[dhehdxhdaus]

Originally Posted by evcelica

1.) Use two "additional variables" in your fluid. (Actually you could probably use just 1, but lets go with 2)
These are passive scalars in the fluid. Set Inlet A to have some arbitrary value of scalar A, with zero B, and Inlet B to have an arbitrary value of scaler B, with zero A. Check the massflowAve of each of those scalars at the two outlets.
2.) Everything that goes in will go out, conservation of mass. it can't accumulate in the pipe. If you are looking for residence time or dead zones, you can use a third scalar C. With that use a subdomain over the whole volume and apply a volumetric source of 1 Scalar C value per second, and results will show you the average residence time for that volume.
The Time variable on streamlines may also be useful, and can help visualize #1.

Gert-Jan's approach will work as well, beat me to it.
But only if you don't need to actually calculate temperatures for other reasons, which you likely don't in your case.

Thanks for your help. I do not know the knowledge about additional value, so I will proceed while looking at the manual. Are there any tutorials I can refer to?

[Gert-Jan]

Did you check the search function of this forum (top right corner).
If you search for "residence time", you can find a lot of information on this topic. To help you, in the query below it is described how to do it:

new variable defination

[dhehdxhdaus]

Originally Posted by Gert-Jan

Did you check the search function of this forum (top right corner).
If you search for "residence time", you can find a lot of information on this topic. To help you, in the query below it is described how to do it:

new variable defination

Thank you for your continued help. Gert-Jan!