The wavenumber ky = ω/cR with cR being the shear-wave velocity of the bedrock.
The wavenumber ky = ω/cR with cR to be the shear-wave velocity of the bedrock.
I am wondering which expression is correct or more preferred by natives.
Using 'to be' implies something expected rather than a current fact, implying 'due to be`:
We expect to have a lot of people come up this weekend with the weather to be quite nice
In mathematics and other sciences, you would either use the present tense as @Jim suggests, 'where
cR is...' or write 'The wavenumber
ky = = ω/(cR),