surface tension - liquid gas code

Please I would like to ask you guys some advertisement on how to use this term in the xml under <properties>:

< surfcoef value="0"/> (Surface Tension coefficient: optional)

From the guide, I couldnt relate how this term will influence the the surface tension value, in which equation it is used.



  • function: KerInteractionForcesFluidMP in GPU version

  • thanks @JOJO

    found it here

    but im still in doubt about what value should i choose to simulate an air-water flow.

    for the two-phase flow liquid-gas tutorials, the only one where i saw the use of this surfcoef was the last one, 06_Surface Tension, but it actually deals with a liquid-liquid (water-heavy water) case and it uses a surfcoef=0.5.

    from Hu and Adams 2006 paper ("A multiphase SPH method for macroscopic and mesoscopic flows"), I saw a numerical example of a droplet of water surrounded by air, where they used surfcoef=1. im using this value, but i´m not sure if there are other things to take into account for this choice.

  • edited January 29


    the surfcoef coefficient is the physical surface tension coefficient (usually denoted by γ or σ) with units of N/m. Within the code is denoted as surfc1 and is called by


    It is only used for calculation of the surface tension force.

    The physical value for water at surface temperature is 0.072N/m. I have not had issues using this value. If there are large instabilities in the interface you can try a larger value like Hu & Adams, but bear in mind that their multi-phase and viscosity model were also different.

  • @athmokos thanks for the explanation.

    in the xml file we edit < surfcoef value="0"/> instead of surfc1. in order to work with 0.072N/m as surfc1 what value should i use for surfcoef? or should i add <surfc> instead of <surfcoef> in the xml? in the code i could find both variables.

    i read in the guide that dualsphysics surface tension formulation was based on CSF model and SPH implementation of Hu and Adams (2006), thats why i went to look further the paper, but i dont know if they refer to surfcoef or surfc1.

    thanks in advance

  • got this from caseconfig at jsph.cpp

    is it surfcoef=surfc1?

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