SimScale CAE Forum

One-way constrained flow


I am working on a project which requires check valves (=one-way valves) in order to prevent backflow in a pipe in a transient simulation. In a given moment, the fluid flows in the opposite direction, which does not happen in real life as a result of the check valves.

Is there a tool/setting in SimScale (in the boundary conditions I suppose) that would constrain the fluid to flow in only one direction?

To be specific, I’d like to constrain the flows in the following sections to be flowing in specific directions:

If you need more information, please let me know.

Many thanks,


Hey Viliam, how about using a momentum source there, to control the direction and velocity of the flow?

Have a look here:
Momentum Sources | Advanced Concepts Documentation | SimScale.

Best regards,

Hi Fillia,

Thank you for your response. The momentum source only lets you specify an average velocity which is not what I need.

In my case, from t=0sec to t=2sec, the fluid will be flowing from point A to point B. But from t=2sec to t=4sec, I need to create a virtual boundary or a one-way valve as the flow will want to flow from point B to point A which I do not want. The momentum source does not let me vary the average velocity as a function of time.

Is there any way to do this?



This used to be possible a few years ago with the 6 DoF solver (e.g. this project), however this solver was discontinued quite a while back.

Make sure to add your feedback to the public roadmap page, so that it’s tracked accordingly & planned for.

Now, it’s difficult to suggest alternatives without a project link & more information about the objectives, but would it be a possibility to simplify the non return valve with a time-dependent velocity inlet boundary condition (i.e. remove the valve and leave just a patch for the boundary condition)? For example, from 0 to 2 seconds, you have a value of x; from 2 seconds onwards, you have 0 velocity.


1 Like