Conjugate heat transfer

ANS 1 : CHT analysis allows us to simulate the heat tranfer between the solid body and the fluid . These types of simulations are governed by the convection type of heat tranfer . It\'s done between the interface of the solid body and the fluid domain exchanging thermal energy .

ANS 2 :

# CASE 1 : Baseline Mesh

# Geometry

We have extracted the volume of the exhaust pipe and thus , we have

1. Solid volume ( exterior of the pipe )

2. Fluid volume ( extracted volume )

# Mesh :

Named selection :

1 inlet

2 outlet

3 wall symmetry convection

number of elements : 137391

we have used the shared topology , for the conformal mesh .

# Fluent :

Physics :

Steady state condition

pressure based solver

absolute velocity

k epsilon (RANS ) , turbulent based solver

thermal conditions valid

Boundary conditions :

inlet velocity : 5 m/s

temperature : 700 k

Material :

Fluid : air

Solid : aluminium

We have changed the thermal conductivity of the wall symmetry convection to ( 20 )

Residuals

Contours

The velocity contour is plotted

# Results :

Velocity contours with the streamlines is shown in the post results

* Here we can see the mesh being coarse , so the wall heat tranfer coeff. being seen in a very coarse manner.

# CASE 2 : Refined mesh with inflation layerG

# Geometry

The geometry that we have used is the same as the above mesh that we have used .

# Mesh

Element number : 424262

We have provided the inflation layer , of total thickness , total thickness ( 5mm )

# Fluent

1 Physics

2. Boudary layer condition

We have used the same condition as that of the case 1.

# Residuals

# Temperature contour

# Results :

1. Velocity contour

2. Wall Heat transfer coeff. contour

# CONCLUSION :

As we have seen in the case 1 the mesh was coarse and thus the heat transfer coeff. is coarse and as seen in case 2 we see the smooth line of that represents the heat transfer coiff. . Also , the heat transfer coeff. is maximum where the velocity is maximum. As , the condition is steady state so as per the mass flow rate is same at the inlet and the outlet thus the velocity is maximum at the outlet.

ANS 3 : We can verify the that the results are satisfying as ;

1. The residuals are converging

2. The simulation is acting as steady state.

3. As the condition is stedy state thus [ m (in) = m (out) ] , so the velocity at the outlet is maximum.

4. Thus the heat trnsfer coeff. is maximum ( as the reynolds number is greater).

Factors on which the results depend upon are ;

1. solid body which is not the part of the wall symmetry convection are set to have adiabatic conditions ( thus the heat transfer is 0 there )

2. the velocity of the flow at the outlet is maximum ( as per steady state there is only 1 outlet ).

3. thus the reynolds number is greater

4. so the heat tranfer coeff is maximum there.