The velocity varying with time can be represented as$$U = As\sin({2\pi{}t}) + l$$

inlet_u
    {
        type uniformFixedValue;
        uniformValue sine;
        uniformValueCoeffs
        {
        frequency 50000;  
        amplitude -0.5; //A
        scale (0 1 0); // s
        level (0 -0.5 0); // l
        }
    }

The boundary condition for $p$ is still zeroGradient

inlet_u
{
        type zeroGradient;
}

For Functions Given in Tables

See the document >>

Using The groovyBC Library

See the Wiki page >>