Hi -
You should be able to do this using a UDF.
See the Conveyor Belt tutorial for an example of varying belt speeds. You can do a similar thing to set the variable BC_MASSFLOW_S.
You don’t need to use the key data approach if you just want to hard-code a simple sinusoid in usr1_des.f. If you do that you will just need to rebuild the solver when you change the parameters.
– Charles