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Re: external cross flow problem
Emre, I suapect that the drop in water temperature is so small you are just not seeing it. Try setting the results scale to a very narrow band (like 340K to 339.9K) and see if that will show the temperature gradient in the water.
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Re: external cross flow problem
hello mr Keown, I think problem is not about the scale. Fluid is at 340 K all over tube and there is no heat transfer between fluid and air. I attached the file above. Pls could you check it.
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Re: external cross flow problem
Expected result should be That decreasing temp distribution along the tube.i mean if inlet temp Of Fluid is 67 the outer temp should be less than it
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Re: external cross flow problem
how much change are you expecting?
also can you check your inputs, i think the flow rate was 0.3, not the 0.21 you specified. please also make sure to check the units.
i would also recommend that you put goals at the inlet and outlet for velocity, pressure, mass flow rate...etc
one in consistency with your description is that your external flow is actually going past your lids. so it is cooling on the outside of your lids in additino to the tube. is that really happening? you may want to setup a second box to control the flow. (similar to the tutorial on cross flow heat exchanger)
and i don't believe you need the fluid subdomain. try it without it and see what happens. but you may need local initial conditions instead.
nothing else was really glaring, so i would be more interested in your expectations.
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Re: external cross flow problem
In this case, Convection is consider on tube outer suface.
In my calculation , 476.603W is going to surround by convection. So outlet water temperature is lower about 0.54degC than inlet Temperature. and Q_water=0.21[kg/s]*4188[J/kg*k]*0.54[k]=476.86W is approximately equal to convection heat trasnfer rate.
if you see unifom temperature of water, consider adiabatic boundary condition on tube outer surface.[wall-ideal wall]