help required on fluent AUV simulation!!!!
 

hai,
I am doing simulations to predict the drag behavior when AUV's are placed in series.
I have attached the mesh i have did in GAMBIT.
Details of AUV:
length overall=1.42m
dia max=0.16m
velocity of flow=1.5m/s
medium is "water"
I have attached a boundary layer of height 0.00065m on the walls
B.C's:
inlet=velocity_inlet; outlet=ressure_outlet; top & bottom=symmetry;
hull=wall
MODEL: viscous--Laminar;

My problem is for above situation Re>2000, my use of "Laminar" model is correct or not.
My solution is not converging when i attach the boundary layer(continuity residual is not even going lower than 0.02)
And almost in every simulation Pressure drag On first AUV is very less, while on follower is more and some times i.e at some close sepertations between AUV1 and 2 pressure drag on first becoming "negative"(specifically when i attach no boundary layer).

Please anybody help me out of this situation please by suggeting me with which "viscous" model to be used in this case and rest of the problems i faced.

Thank you all in advance