Room Temperature Study(Part 2)

Room: Operating Conditions

The operating conditions for the flow at room are:

-The working fluid is Air

-Worker Temperature = 310 K

-Computer Monitor Temperature = 303 K

-Computer Vent: 0.033 kg/s @ 313 K (per computer)

-Ceiling Vents: profile data, Temperature=294 K

Room Geometry and Details

Starting FLUENT in Workbench

1. Return to the Project window
2. Drag FLUENT into the Project Schematic
3. Change the name to Room
4. Double click on Setup
5. Choose 3D and Double Precision under Options and retain the other default settings

Import Mesh

This starts a new FLUENT session and the first step is to import the mesh that has already been created:

1. Under the File menu select Import> Mesh
2. Select the file duct.msh and click OK to import the mesh
3. After reading the mesh, check the grid using Mesh>Check option

or by using Check under Problem Setup>General

Reading the Profiles

Read the profile files that were written in the Duct’s case at Vent Boundaries

1. Under the File menu select Read> Profile
2. Select the file vent1.prof and click OK to read the profile
3. Similarly read vent2.prof file

Models

1. Select Pressure Based, Steady state solver
   Problem Setup>General>Solver

1. Specify turbulence model
   Problem Setup > Models > Viscous
   Double click and Select k-omega (2 eqn) under Model and SST under k-omega model and retain the default settings for the other parameters

1. Enable the Energy Equation.
   Problem Setup > Models> Energy

Materials

Define the materials.

Problem Setup > Materials

1. Double click on air to open Create/Edit Materials panel
2. Select incompressible-ideal-gas from the dropdown menu of Density
3. Retain other default values of Specific heat and Viscosity. Select ‘Change/Create’ to implement the changes then Close

NOTE: The incompressible ideal gas law for density is used when pressure variations are small enough that the flow is fully incompressible but you wish to use the ideal gas law to express the relationship between density and temperature

Operating Conditions

Problem Setup >Cell Zone Conditions

Click on Operating Conditions… and set the Operating Pressure (Pascal) to 101325

Enable Gravity and specify Z-component of Gravitational Acceleration as -9.81 m/s2

Enter Operating Density as 1.225 kg/m3

Note: Enabling gravity will allow the solver to take into account the buoyancy effect due to the change in the density of the air.

Boundary Conditions

Under Problem Setup > Boundary Conditions

1. Select vent1 under Zone and choose velocity-inlet from the drop down menu under Type. For this boundary we will specify the parameters using the previously read profile file
2. Now double click on vent1 under Zone
3. Go to Momentum tab, set Components as Velocity Specification Method
4. Select vent1 x-velocity from the dropdown menu for X-Velocity. (make sure you select the velocity variable “vent1 x-velocity” not the grid variable”vent1 x”. Do likewise for all the other variables (y-velocity, z-velocity, turbulent kinetic energy and specific dissipation rate).

5. In the Thermal tab, set a constant Temperature of 294K:

Under Problem Setup > Boundary Conditions

1. Similarly, select vent2 under Zone and set all the quantities. This time choose the profile quantities starting with vent2

Under Problem Setup > Boundary Conditions

1. Select outlet under Zone and choose Pressure-outlet from the drop down menu under Type. For this boundary we will specify the parameters using the previously read profile file
2. Now double click on outlet under Zone
3. Go to Momentum tab, set Gauge Pressure (Pascal) as 0
4. Set the backflow conditions for the turbulence quantities to have a Backflow Turbulent Intensity and Backflow Turbulent Viscosity Ratio of 5% and 5 respectively
5. In the Thermal tab, set a constant Backflow Total Temperature of 294 K

Under Problem Setup > Boundary Conditions

1. Select computer1intake under Zone and choose Mass-Flow inlet from the drop down menu under Type.
2. Set the Mass Flow Rate as 0.033 kg/s and keep the Direction Specification Method as Outward Normals
3. Set Turbulent Intensity (fraction) and Turbulent Viscosity Ratio as 5% 10 respectively

To save time, the conditions for computer1 can be copied over to the boundary conditions for the other 3 computers in the simulation.

1. Make sure that the inlets for the other computers are all of type mass-flow-inlet

2. In the Boundary Conditions Panel, click the Copy... button. This will open the Copy BCs panel

3. In the From Zone list, select the zone that has the conditions you want to copy: computer1intake

4. In the To Zones list, select the zones to which you want to copy the conditions to: computer2intake, computer3intake, computer4intake

5. Click Copy. FLUENT will set all of the boundary conditions for the zones selected in the To Zones list to be the same as the conditions for the zone selected in the From Zone list.

Under Problem Setup > Boundary Conditions

1. Repeat the instructions on the previous 2 slides in order to set the conditions for the computer vents.
2. So, first make sure all vents are of type ‘mass-flow-inlet’.
3. Set the conditions for computer1vent as in the image below.
4. In the Thermal tab, set a constant temperature of 313 K
5. Copy this boundary condition from computer1vent to the other 3 computers.

Under Problem Setup > Boundary Conditions

1. Select monitors under Zone and choose wall from the drop down menu under Type.
2. Now double click on monitors under Zone
3. Go to Momentum tab, set it as Stationary wall with No Slip
4. In the Thermal tab, set a constant Temperature of 303 K

Under Problem Setup > Boundary Conditions

1. Select workers under Zone and select wall from the drop down menu under Type.
2. Double-click on workers under Zone.
3. On the Momentum tab, specify a stationary wall with no slip.
4. On the Thermal tab, set a constant wall temperature of 310 K.

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