vk.com/club152685050Using the Eulerian Granular| vkMultiphase.com/id446425943Model with Heat Transfer

c. Retain the default No Slip condition and click OK to close the Wall dialog box.

10.Set the boundary conditions for the heated wall (wall_hot) for the secondary phase (solids) same as that of the primary phase.

Setup → Boundary Conditions → wall_hot

For the secondary phase, you will retain the default no slip condition as for the primary phase.

11. Set the boundary conditions for the adiabatic wall (wall_ins).

Setup → Boundary Conditions → wall_ins

For the adiabatic wall, retain the default thermal conditions for the mixture (zero heat flux), and the default momentum conditions (no slip) for both phases.

21.4.9. Solution

1.Select the second order implicit transient formulation and higher-order spatial discretization schemes.

Solution → Solution → Methods...

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Setup and Solution

a.Select Second Order Implicit from the Transient Formulation drop-down list.

b.Modify the discretization methods in the Spacial Discretization group box.

i.Select Second Order Upwind for Momentum.

ii.Select Quick for Volume Fraction and Energy.

2.Set the solution parameters.

Solution → Controls → Controls...

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a.Enter 0.5 for Pressure.

b.Enter 0.2 for Momentum.

3.Ensure that the plotting of residuals is enabled during the calculation.

Solution → Reports → Residuals...

4.Define a custom field function for the heat transfer coefficient.

User Defined → Field Functions → Custom...

Initially, you will define functions for the mixture temperature, and thermal conductivity, then you will use these to define a function for the heat transfer coefficient.

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Setup and Solution

a.Define the function t_mix.

i.Select Temperature... and Static Temperature from the Field Functions drop-down lists.

ii.Ensure that air is selected from the Phase drop-down list and click Select.

iii.Click the multiplication symbol in the calculator pad.

iv.Select Phases... and Volume fraction from the Field Functions drop-down list.

v.Ensure that air is selected from the Phase drop-down list and click Select.

vi.Click the addition symbol in the calculator pad.

vii.Similarly, add the term solids-temperature * solids-vof.

viii.Enter t_mix for New Function Name.

ix.Click Define.

b.Define the function k_mix.

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vk.com/club152685050Using the Eulerian Granular| vkMultiphase.com/id446425943Model with Heat Transfer

i.Select Properties... and Thermal Conductivity from the Field Functions drop-down lists.

ii.Select air from the Phase drop-down list and click Select.

iii.Click the multiplication symbol in the calculator pad.

iv.Select Phases... and Volume fraction from the Field Functions drop-down lists.

v.Ensure that air is selected from the Phase drop-down list and click Select.

vi.Click the addition symbol in the calculator pad.

vii.Similarly, add the term solids-thermal-conductivity-lam * solids-vof.

viii.Enter k_mix for New Function Name.

ix.Click Define.

c. Define the function ave_htc.

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Setup and Solution

i.Click the subtraction symbol in the calculator pad.

ii.From the Field Functions drop-down lists, select Custom Field Functions... and k_mix and click Select.

iii.Use the calculator pad and the Field Functions lists to complete the definition of the function.

iv.Enter ave_htc for New Function Name.

v.Click Define and close the Custom Field Function Calculator dialog box.

5.Define the point surface in the cell next to the wall on the plane .

Domain → Surface → Create → Point...

a.Enter y=0.24 for New Surface Name.

b.Enter 0.28494 m for x0 and 0.24 m for y0 in the Coordinates group box.

c.Click Create and close the Point Surface dialog box.

6.Create a surface report definition for the heat transfer coefficient.

Solution → Reports → Definitions → New → Surface Report → Facet Average

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a.Enter surf-mon-1 for Name of the surface report definition.

b.In the Create group box, enable Report File, Report Plot and Print to Console.

c.Select Custom Field Functions... and ave_htc from the Field Variable drop-down lists.

d.Select y=0.24 from the Surfaces selection list.

e.Click OK to save the surface report definition settings and close the Surface Report Definition dialog box.

surf-mon-1-rplot and surf-mon-1-rfile that are automatically generated by Fluent appear in the tree (under Solution/Monitors/Report Plots and Solution/Monitors/Report Files, respectively).

f.Rename the report output file.

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Setup and Solution

Solution → Monitors → Report Files → surf-mon-1-rfile Edit...

i.Enter htc-024.out for Output File Base Name.

ii.Click OK to close the Edit Report File dialog box.

7.Define a cell register for the lower half of the fluidized bed.

Solution → Cell Registers New → Region...

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a.Enter 0.3 m for Xmax and 0.5 m for Ymax in the Input Coordinates group box.

b.Click Save to close the Region Register dialog box.

c.Click Close to close the Region Register dialog box.

This register is used to patch the initial volume fraction of solids in the next step.

8.Initialize the solution.

Solution → Initialization → Options...

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Setup and Solution

a.Select all-zones from the Compute from drop-down list.

b.Retain the default values and click Initialize.

9.Patch the initial volume fraction of solids in the lower half of the fluidized bed.

Solution → Initialization → Patch...

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a.Select solids from the Phase drop-down list.

b.Select Volume Fraction from the Variable selection list.

c.Enter 0.598 for Value.

d.Select region_0 from the Registers to Patch selection list.

e.Click Patch and close the Patch dialog box.

At this point, it is a good practice to display contours of the variable you just patched, to ensure that the desired field was obtained.

10.Display contours of Volume Fraction of solids (Figure 21.3: Initial Volume Fraction of Granular Phase (solids) (p. 743)).

Results → Graphics → Contours → Edit...

a.Enable Filled in the Options group box.

b.Select Phases... from the upper Contours of drop-down list.

c.Select solids from the Phase drop-down list.

d.Ensure that Volume fraction is selected from the lower Contours of drop-down list.

e.Click Display and close the Contours dialog box.

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Setup and Solution

Figure 21.3: Initial Volume Fraction of Granular Phase (solids)

11.Save the case file (fluid-bed.cas.gz).

File → Write → Case...

12.Start calculation.

Solution → Run Calculation → Advanced...

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a.Set 0.00015 for Time Step Size(s).

b.Set 12000 for Number of Time Steps.

c.Enter 50 for Max Iterations/Time Step.

d.Click Calculate.

The plot of the value of the mixture-averaged heat transfer coefficient in the cell next to the heated wall versus time is in excellent agreement with results published for the same case [1].

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