URGENT!! Help on Throttle body poject.
 

I am working on a Formula SAE project, I reqired to create a 3D model and determine the air mass flow through the throttle body, which basically is a converging-diverging nozzle. what i did so far was created a cylinder as domain with the vol of the throttle deducted at the end of it, then i mashed with Hybrid/tri, then set the 3 sides of the cylinder as pressure inlet (1 atmo), the sides of throttle as wall and the end of the diverging section as pressure outlet. then i ran a inviscous flow model, but the solution diverge after 10 iterations and have floating point errors, also the velocity of flow is not right. can anyone explain to me what floating point error is and how imporant convergant is? also what is the different between pressure-far field and pressure inlet and outflow-vent. do you racken i have set up the model correctly?