Time-dependent heat flux [Neumann boundary condition]

Hi guys,

I am new in COMSOL, and the same question I am posting, had already circulated several times. Unfortunately, I am not able to solve my problem with the "help" of those posted answers.

1. I would like to solve time-dependent heat transfer problem in 2d
2. On some boundaries there (see figure) are prescribed time-dependent incoming heat fluxes, in the form of goniometric functions: , where and are parameters I would like to vary later.
3. In the module heat transfer in solids, I took "heat flux", out of three possibilities there, I don't know which I should chose, and how to implement my heat flux boundary conditions, say for is 1000 W/m and 20 Hz.