udf for uniform shear at inlet

ayapan

hi everyone.

i am simulating low reynolds number (laminor) flow past bluff body. my interest is to find the effect of uniform shear in inlet velocity.

i tried with the udf, and was able to get till zero velocity ( for low shear rate). when i increase shear rate further, i have to get negative velocity at inlet, but the plot xy velocity data is not showing any negative velocity. instead it is giving positive velocity of same magnitude. is it means the solver will take positive velocitty or ???

any suggestion regarding this will be appreciated. thanking you Bye Ayapan