Introduction
In this workshop you will be analyzing the effect of computers and workers on the temperature distribution in an office. In the first stage airflow through the supply air ducts will be simulated and the outlet conditions for the duct will be used to set the inlet conditions for the room. Although both components could be analyzed together, separating the two components allows different room configurations to be analyzed without solving the duct flow again.
Duct Simulation
The operating conditions for the flow are:
-Fluid Temperature = 21 [C]
-Inlet: 0 [atm] Total Pressure
-Outlet: 0.225 [kg/s] (per vent)
Starting CFX in Workbench
1.Open Workbench
2.Drag CFX into the Project Schematic from the Component Systems toolbox
3.Change the name of the system to duct
4.Save the project as RoomStudy.wbpj in an appropriate directory
5.Double-click Setup
Import Mesh
The first step is to import the mesh that has already been created:
1.Right-click on Mesh in the Outline tree and select Import Mesh > ICEM CFD
2.Select the file duct_mesh.cfx5
3.Make sure Mesh Units are in m and click Open to import the mesh
Create Domain
You can now create the computational domain:
1.Double-click on Default Domain in the Outline tree to edit the domain
2.On the Basic Settings tab, set the Fluid 1 Material setting to Air Ideal Gas
3.Switch to the Fluid Models tab
4.Set the Heat Transfer Option to Isothermal
-Heat Transfer is not modeled, but since the working fluid is an ideal gas we need to provide a temperature so its properties can be calculated
5.Set the Fluid Temperature to 21 [C]
6.Change the Turbulence Model Option to Shear Stress Transport
7.Click OK to commit the changes to the domain
Create Boundary Conditions
Solver Control
1.Double click on Solver Control from the Outline tree
2.Enable the Conservation Target toggle
3.Click OK to commit the settings
Monitor Point
Monitor points are used to monitor quantities of interest during the solution. They should be used to help judge convergence. In this case you will monitor the velocity of the air that exits through the vent. One measure of a converged solution is when this air has reached a steady-state velocity.
1.Double click on Output Control from the Outline tree
2.Switch to the Monitor tab and enable the Monitor Options toggle
3.Under Monitor Points and Expressions, click the New icon
4.Keep the default name Monitor Point 1
5.Set the Option to Expression
6.In the Expression Value field, type in:
areaAve(Velocity w)@VENT1
7.Click OK to create the Monitor Point
Write Solver File
You can now save the project and proceed to write a definition file for the solver:
1.Close CFX-Pre to return to Project window
2.Save the project
3.Right-click on Solution and select Edit
4.Choose Start Run
CFX Solver Manager
1.Examine the residual plots for Momentum and Mass and Turbulence
2.Examine the User Points plot
3.When the run finished close the Solver Manager
4.View the results in CFD-Post by double-clicking Results in the Project window
CFD-Post
Now we will export a Boundary Condition profile from the outlet regions for use in the next simulation.
1.Select File > Export
2.Change the file name to vent1.csv
3.Use the browse icon to set an appropriate directory
4.Set Type as BC Profile and Locations as VENT1
5.Leave Profile Type as Inlet Velocity and click Save
6.Similarly export a BC profile of VENT2 to the file named vent2.csv
7.Quit CFD-Post and return to the Project Schematic
Operating Conditions
The operating conditions for the flow in the room are:
-The working fluid is Air Ideal Gas
-Computer Monitor Temperature = 30 [C]
-Computer Vent Flow Rate: 0.033 [kg/s] @ 40 [C] (per computer)
-Ceiling Vents: Profile Data, Temperature=21 [C]
http://www.cadfamily.com/html/Article/Introduction%20to%20CFX-Room%20Temperature%20Study_777_1.htm
http://www.cadfamily.com/html/Article/Introduction%20to%20CFX-Room%20Temperature%20Study_777_2.htm
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