Frequently Asked Questions (FAQ)

Please read this FAQ before sending a Support request.

I would like to start a simulation, but the “run” button is grey. What should I do?
Take a look at the bottom-left “Validity” window: any error message in that window will disable the run button. If you see an error in the Validity window, click on the blue underlined item in the message, which will focus the 3D model on the object with erroneous input, and open its property window (on the right-hand side of the GUI). Check the properties (look for a red cross ) and correct the error in that property.

I can start a simulation, but an information window pops up with the message: “Sentinel RMS Development Kit: Error [18]: No license code is available for feature APIsolvAC ver 1.0 on host no-net.
Two things can cause this problem:
1. You have not added the APIsolvAC license code yet
2. You have not “activated” the APIsolvAC license yet
Please refer to the installation instructions, and to the license activation instructions to add and activate a license.

I select “PulsationResults” from the “Color usage” menu, but no results appear
1. You may not have calculated any results yet, so first run a simulation
2. You may have calculated only “Initialization” run results. To view these results:

  • First select “Default” coloring, and then select “PulsationResults” again, to toggle the results loader.
  • In the “Select results” window that pops up, Select run type: InitRun
  • Now click OK, and the initialization run results will be shown on the pipe system

Why does PulsimSuite filter all acoustic results?
Propagating pulsation waves through a pipe system have low damping. In PulsimSuite, the damping of pulsations in pipes occurs only via wall friction (and specific friction elements, such as orifice plates, and nozzles). Wall friction is characterized by the fanning friction factor property of each pipe (0.004 for circular steel pipes). Using a constant (mean) fanning friction factor at all frequencies (we are doing a time-domain simulation) and flow velocities, the PulsimSuite acoustic solver is accurate for frequencies up to about the 16th harmonic of a running compressor/pump, but tends to underestimate damping of higher frequencies (especially in closed side branches where the mean flow is zero). We therefor apply a default linear filter from the 16th (value =1) to the 32nd harmonic (value=0). Should you be interested in higher frequencies, you can adjust the default filter settings, by saving a text file next to your model, see Help -> Filtering Acoustic Simulation Results.

Can I change the filter settings after all my simulations have been run and processed?
Yes, you can re-filter your results, with your user-defined filter settings. If you want to use “tighter” filtering (filtering at lower frequencies than default), you can simply place your user-defined filter in the main model directory, and press the “Filter” button (  ).
Please use the menu option Help -> Reference -> Filtering to read about how to specify a user-defined filter.
If you want to filter at higher frequencies than default, you currently first need to move the results from the “Unfiltered” directories back to the <modelname>_Case_IDx directories.

Which Word versions are supported by the PulsimSuite report generator?
The report generator is built for Word 2010, but also works for Word 2013, if you disable “reading mode”.

How should I specify MaxDx and ConvCrit in the Run Cases tab?
First of all, please note that the pulsim solver “meshes” each pipe into an integer number of pipe segments, see Help -> Reference -> Simulation Settings. The larger the segments (MaxDx), the larger the meshing error you are introducing on the actual pipe lengths.

In general the following strategy for MaxDx and ConvCrit is suggested:

  • Run a few sensitivity runs w.r.t. MaxDx (50mm, 80mm, 100mm), to see if the results depend on the grid size. The simulation speed depends significantly on the DX of the simulations (small DX means small dt, thus more timesteps in a revolution of the crank).
  • Run a few sensitivity runs w.r.t. ConvCrit (5E-4, 5E-3, 1E-3, 5E-2).

In both situations, run for NrSteps of only approximately 5 or 10 over the deviation range, so you will know quite soon what will be suitable values to use. Now compare results for mean pressure, mean flow, and pulsation levels for the different MaxDx and ConvCrit settings, and find the largest MaxDx and ConvCrit where the results are still accurate.

Be aware, the adequate values can be different for each model, and even for each duty/load combination. So it may take some time in the beginning, but it will save you quite some computation time in the end.

In the results the flow seems to be dependent on the deviation of the speed of sound (when running a VOS sweep). What can be the reason for such a phenomena?
The VOS sweep is there for two physical reasons: to take into account a deviating operating temperature and/or a deviating gas composition. We use the values in data sheets for the nominal values, but small deviations lead to different speeds of sound. The mass flow through the piping depends on the density of the gas, which depends on temperature and composition as well. For that reason we take this into account. If you specify the VOSL sweep (L for liquid), you will only change the speed of sound but not the density. We use this mainly for liquids, as the speed of sound is not always known but the density is well predictable and more constant for different temperatures.

For the CY node there are KWsuc and KWdis properties defined. Are these values for the compressor valves? Do you get them from a valve data sheet or from somewhere else?
Yes these are for the compressor valves, so you do not need to add a KW to the pipe that represents the valve passage (connection between inside the cylinder and outside the cylinder) in your geometrical model. The KW values (or pressure loss at a specific constant flow) for suction and discharge valves are often mentioned on the valve data sheets or the compressor data sheets. If unknown, we use 4 as a default value.

When I run a simulation, I see .dat files and .psr files appearing in the directory where my model (.pmf file) is saved, while they should be in the CaseID_xx directory. What is wrong?
You may be working with a model that is saved on a network location. If you have opened your model via the “UNC pathname”, which looks like \\\users\username\ , PulsimSuite cannot place the files in the correct directories. To prevent this error, you need to use the “map network drive” functionality of Windows. Assign a drive letter to the network directory you are working on, and in PulsimSuite open the model from this drive letter.

Note: We advise not to run simulations on a network location, as this will slow down your simulations. Copy your model to the local drive of the PC to run simulations.