[sara22]

hello guys
i simulate shell&tube heat exchanger in fluent. i use velocity inlet boundary condition. now i question that i must select which options in turbulence part of velocity inlet boundary condition?
K and ep.
intensify and length scale.
intensify and velocity ratio.
intensify and hydraulic diameter.

[A CFD free user]

It depends on your problem and inlet geometry but in most cases, the third option is more straightforward.

[sara22]

tanks about your Ans.
I don't know why mass flow rate at inlet and outlet not be equal?!
this heat exchanger has two fluid domain (Water&Oil).
water: inlet - velocity inlet
outlet - pressure outlet
--------------------------
Oil: inlet - velocity inlet
outlet - pressure outlet
-------------------------------
That this domains are coupled(Thermal condition) together.
for example mass flow rate at inlet and outlet :
water inlet= 1.132
water outlet=0.746
oil inlet=0.171
oil outlet=0.521

[virendra_p]

Use intensity and hyd. dia bc. option...you can find empirical relations for I and D involving velocity and geometry data in fluent user guide....just looking at those mass flow rates gives me the impression that water is entering into oil flow domain...some sort of leakage...please check your geometry construction ..... Good luck!

[sara22]

tanks about your ans.
my geometry is ok. i think my mesh file is not suitable.but i cant improve mesh file. its very complex.if possible i send ansys file(project-workbench) for you that you check it.email address please?

[virendra_p]

vdp6786@hotmail.com.... I'll have a look

[sara22]

i send project file for you .
thanks about your att.

[virendra_p]

Hi....i got the file but unfortunately your ansys is newer so files couldn't be supported by my system...is there any way around?

[sara22]

Thanks. i sent 'stp' file of my model for you

[virendra_p]

Hi...i got the geometry....just one doubt...the end where the tube-side fluid (i guess oil in your case) reverses (the semi-sphere at top end)....shouldn't there be plates installed...or else shell-side fluid (water) will intermix...please clear