# Bubble dynamic under forced vibration

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 July 7, 2015, 15:18 Bubble dynamic under forced vibration #1 Member   Arsalan Join Date: Jul 2014 Posts: 74 Rep Power: 11 Dear Foamers, I want to study the shape oscillation an translation motion of a single bubble in a liquid container under vibration while the imposed displacement of the container is y=Acos(wt). I found that there are two methods for this purpose,first i used the interDyMFoam solver with oscillatingLinearMotion as the solidBodyMotionFunction,but with this method i get very wrong results in the bubble shape and motion. Then i add an acceleration source term to the interFoam solver with modifying the UEqn.H file : dimensionedVector accY ( "accY",dimensionSet(0, 1, -2, 0, 0),vector(0, 1, 0) ); scalar Pi = 3.14; dimensionedVector acc = (-(w^2)*A*Foam::cos(w*runTime.value())*accY); fvVectorMatrix UEqn ( fvm::ddt(rho, U) + fvm::div(rhoPhi, U) + turbulence->divDevRhoReff(rho, U) == (acc*rho) ); UEqn.relax(); if (pimple.momentumPredictor()) { solve ( UEqn == fvc::reconstruct ( ( fvc::interpolate(interface.sigmaK())*fvc::snGrad(a lpha1) - ghf*fvc::snGrad(rho) - fvc::snGrad(p_rgh) ) * mesh.magSf() ) ); } with this method bubble shape and oscillaton in the first time steps are good but the velocity magnitude is wrong and bubble shape and oscillation by the time get wrong results,im not sure that the UEqn.H file is modified correct or not,or which method is suitable for the forced vibration of the container,so far i couldnt find an answer for this problems!what is the difference between two methods and why the first method get wrong results?! I would appreciate your comments! Thanks a lot, Arsalan.

 July 9, 2015, 15:09 #2 Member   Arsalan Join Date: Jul 2014 Posts: 74 Rep Power: 11 Does nobody has a suggestion or idea?? I would be very much thankful..

 Tags bubble dynamics, dynamic mesh, interdymfoam, interfoam, moving mesh