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How to Assess a Pressure Drop in the Post-Processor?

This article shows how to assess a pressure drop value with SimScale using the post-processor.


Now let’s see the steps to obtain the values of the pressure in the areas limiting the region where we aim to study the changes in pressure. In the following image, we have a representation of a pipe with different regions to help us explain this process, going step-by-step.

pipe model with a representation of the internal flow
Figure 1: Pipe model flow situation.

In order to determine the drop in pressure between the inlet and outlet region of the pipe, we have the need to open the post-processor and to create two cutting planes in the areas that limit the volume we want to analyze, with the scalar value as Pressure or Pressure[node].


In case you want to know the difference between the Pressure and Pressure[node], read this article were we explain the difference between cell and node values.

post processor steps to create a cutting plane in the model to present
Figure 2: Post-processor workflow to generate cutting planes.

Using the cutting planes we have the average values of the pressure in the selected areas of the model. By subtracting the values in the two regions we obtain the pressure drop of the simulation.

pressure results of a cutting plane in the post-processor
Figure 3: Average pressure values.

$$\Delta\ P=P_1-P_2=1.48e^+3 – 4.227e^+2 =1.057e^+3 $$

Applying the averaged values available above, we determine the value of the pressure drop in this model between these regions. It is approximately 1057 Pa.

Another available option to obtain the pressure drop more precisely between the inlet and outlet face is to use the Result Control options and directly obtaining the pressure values in the inlet and outlet region.

this pictures explains how to setup a area average on the inlet and outlet of the pipe model
Figure 4: Surface data setup.

Once the simulation finishes, you can access these results controls and extract the pressure values from the plots available under run -> area averages.

area average results for pressure differences
Figure 5: Pressure value on the inlet and outlet face for every iteration.

By calculating the difference between the two pressure values of the last iteration, we get the pressure drop of the model.


If none of the above suggestions solved your problem, then please post the issue on our forum or contact us.

Last updated: July 7th, 2020

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