CFD Septic tank modelling

  • Last Post 15 April 2018
Zainabf posted this 20 March 2018


I have just downloaded the ANSYS FLUENT 19. Software. i wanted to know if there are any tutorials to simulate the flow of water in septic tanks ? 



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Raef.Kobeissi posted this 20 March 2018

Can you provide more information about the Physics of your problem? Is it an open tank or  pressurised ? 

Raef Kobeissi

Zainabf posted this 21 March 2018

We are designing a septic tank to collect wastewater effluent through an inlet pipe. We want to model the the flow of water within the tank from the moment it enters until it exits through an outlet pipe. It is not a pressurized tank. Also, we want to show the settling of sludge at the base of the tank. i have attached below a sample of a septic tank that we are trying to model. Septic Tank Model

Zainabf posted this 27 March 2018

Any updates?


Raef.Kobeissi posted this 29 March 2018


Your model contains large solid particles mixed with a fluid so I wouldn't recommend to use the DDPM model because it can only model small particles. You might want to explore the MPM ( Macroscopic particle model) this is a separate module that can be added in Fluent. I will try to find out more information about it and come back to you. 

As for the filtering process, you need to use the porous medium model:













Raef Kobeissi

Zainabf posted this 30 March 2018


The filtering process at the outlet is not required. My aim is to just model the flow of wastewater through the inlet pipe (while the tank is 70-80% full), how the effluent is then going to go through the baffle and exit through the outlet pipe. Is it possible to show settling of the particles by any chance ?


Raef.Kobeissi posted this 07 April 2018

Hi Zainab,

Yes, you can see how many particles settled on the bottom wall of your model that is if you are using DPM model. Now for large particles, I wouldn't recommend to you DPM you will need the MPM model.

Raef Kobeissi

Zainabf posted this 08 April 2018


I am trying to run the model with 50% to 80% full tank. However, I am having some trouble at marking my 3D model. Even though i specify the coordinates in region adaptation, when i calculate the results, my tank is empty. Any idea how I can resolve this issue? Also, will it be possible for you to check my model and suggest changes? 

Raef.Kobeissi posted this 08 April 2018

Can you attach your project and I will have a look at it.


Raef Kobeissi

Zainabf posted this 09 April 2018

Do you mind if i email it instead as I am getting an error message saying the file extension is not allowed?

Raef.Kobeissi posted this 15 April 2018

I can't provide my personal email address unfortunately can you try to save the case file, zipp it and attach it in here?

Raef Kobeissi