Viscous Damping Coefficient (VDC) in SPH Contact

Viscous Daming Coefficient (VDC) is freqeuntly used in contact interface definitions (*CONTACT) to damp out oscillations normal to the contact segment. It is specified in percentage of the critical damping where a value of 90 is 90% of critical damping. In one recent applications using SPH for gravity initialization of a filled fluid container, using a critical damping coefficient of 90 (%) significantly reduced the noise in the particle contact interaction with the lagrange elements. The attached image shows the force time history with and without VDC.

(Click image to enlarge)

  • Paolo Capozzi says:

    Dear Suri,

    I had a look on the keyword manual and I found the equation which uses VDC to define the damping coefficient as a percentage of the critical damping coefficient. In the manual it is also given a formula to calculate the critical damping coefficient but it uses the “interface stiffness”. How is this last parameter determined? Is there an equation that allows to calculate it?
    Thank you very much for your help.


    Paolo Capozzi.

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