# time vary boundary condition to simulate waves in interFoam or equivalent

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 June 9, 2014, 03:27 time vary boundary condition to simulate waves in interFoam or equivalent #1 Member   Join Date: Jul 2011 Posts: 92 Rep Power: 6 Hi all, I am currently required to run a simulation that takes in boundary conditions that are time varying from a data file, basically with alpha1 and velocity beneath the surface of the water at every time step. Would like to find out what is the best way I can achieve this. Generally, from many wave tank simulations we normally use groovy BC for regular waves, which we have been using for a while now: From http://openfoamwiki.net/index.php/Contrib/groovyBC For a surface elevation following the second order stokes wave, Code: ```inlet { type groovyBC; valueExpression "(pos().z<=A*cos(-w*time())+0.5*k*A*A*cos(2*(-w*time()))) ? 1 : 0"; variables "l=5;A=0.1;g=vector(0,0,-9.81);k=2*pi/l;w=sqrt(k*mag(g));"; timelines (); }``` And for the velocity under the surface elevation, Code: ``` inlet { type groovyBC; valueExpression "(pos().z<=A*cos(-w*time())+0.5*k*A*A*cos(2*(-w*time()))) ? vector( A*w*exp(k*pos().z)*cos(-w*time()), 0, A*w*exp(k*pos().z)*sin(-w*time())) : vector(0,0,0)"; variables "l=5;A=0.1;g=vector(0,0,-9.81);k=2*pi/l;w=sqrt(k*mag(g));"; timelines (); }``` I am thus not sure in the current case how I can proceed if the parameters are irregular and known, stored in a data file of the surface elevation and velocities at the inlet boundary. Regards.