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New Member
Max Braun
Join Date: Nov 2016
Posts: 1
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Hello everybody,
I am trying to run a simple case with sonicFoam and got some undesired damping. I build a tube, 2 meters long, with an oscillating pressure (p' = 1000*sin(t) Pa) as inlet and a waveTransmissive condition as outlet. I was hoping to see a nice sin wave moving through the domain, but there is some kind of damping, even though there is no viscosity (mu = 0). I attached a picture of some pressure probes located a 0.01m, 0.2m 1m and 1.9m. The violet probe at 0.01m shows my nice sin wave but the other ones, especially at 1m (blue) and 1.9m (yellow) show a different amplitude. I am using OpenFoam 4.1 and the simulation is run at 293.15 K and 100,000 Pa without flow (U = (0 0 0)). I already tried different meshes (1D and 2D, 40-100 cells per wave length), different lInf's in the waveTransmissive condition (0.1-20), different time steps (around 1e-05), different frequencies (170-340 Hz), different amplitudes (100-1000) and different conditions for U and T (zeroGradient, waveTransmissive). Nothing worked so far to preserve the amplitude so I was hoping for some advise. Like I said, there is a picture attached with the pressure probe data and you may find my inlet and outlet condition for the pressure below. Thank you very much in advance. Sincerely, Max --------------------------------------------------------------------------------------------------------------- two of my boundary conditions for p: inlet { type uniformFixedValue; //formerly oscillatingFixedValue uniformValue sine; uniformValueCoeffs { frequency 170; amplitude 1000; scale 1; level 100000; } } outlet { type waveTransmissive; field p; psi thermo:psi; gamma 1.4; fieldInf 100000; lInf 3; value uniform 100000; } |
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Tags |
damping, pressure, sonicfoam |
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