Error: pressure loss over volume flow

*When trying to run the simulation i got this error log.

Hey, can you provide the link to the project please? :smiley:

Cheers!

https://www.simscale.com/workbench/?pid=1498623906592097814&mi=spec%3A9345bce4-2bb2-4fbd-899a-ac8f3bfff210%2Cservice%3ASIMULATION%2Cstrategy%3A15&ps=analysis%2FCompressible--oneOf%2FboundaryConditions%2F4

I suggest you try the first approach listed here, using the Convective heat transfer analysis type: How do I Model a Fan Curve in SimScale? | Knowledge Base
According to this, the outlets are set to Natural convection inlet/outlet.

Let me know if this works :slight_smile:

Best regards,
Fillia

Hi,

Quickly providing some insights here. This error occurs when the pressure versus volumetric flow rate results in an illegal definition for the Darcy and Forchheimer coefficients, which are calculated in the background.

In your case, I manually calculated the coefficients and it turns out that the Darcy coefficient is < 0, which is unphysical.

Generally speaking, the volumetric flow rates should increase in the table, and it’s important that the first data point is 0, 0 (no flow = no pressure drop):

In your case, we currently have that 70 m3/s results in 0 Pa pressure drop, which is unphysical.

I’d suggest re-organizing from smaller to larger values, and also reviewing the values, especially this 70, 0 data point.

Cheers

1 Like

Hi,

I understand what you mean with this, but how would you use the Darcy and Forcheimer coefficients? You don’t have all the parameters and depend upon each other. I made the table by an average of blowerdoortest, I can try to rearrange the forumla so it starts with zero.

Thank you for your help!

Kind regards

Hi,

I’m referring to the underlying method, behind the pressure loss curve porous media model. The values that you define are used to calculate the Darcy and Forchheimer terms.

By taking your data and computing the Darcy and Forchheimer coefficients, you would notice that the Darcy term is smaller than zero, which is not valid.

Part of it was caused by the 70, 0 data point, so if you change that one and rearrange the other data points from smaller to larger flow rates, it should help.

Cheers