Applying a spatially varying temperature constraint

Estimated time to complete: 10–20 minutes

In this tutorial, you will use a spatial field to define the thickness of elements.

1: Setup

  1. On your desktop or the appropriate network drive, create a folder named exmanifold.

  2. Click the link below:

    Download the part

  3. Extract the files to your exmanifold folder.

  4. Start Simcenter 3D or NX.

  5. Open ExManifold_sim1.sim.

2: Reset dialog box memory

The options you select in dialog boxes are preserved for the next time you open the same dialog box within a given session. Restore the default settings to ensure that the dialog boxes are in the expected initial state for each step of the activity.

File

Preferences→User Interface

  • Options

  •   Reset Dialog Memory

  • OK

     
3: Create a spatially varying temperature constraint

For this tutorial, the model has been meshed for you and convection boundary conditions have been applied to the top faces of the manifold.

You will apply a spatially varying temperature constraint to the internal surfaces of the exhaust manifold. The mathematical expression representing the temperature variation is written in terms of the cylindrical coordinate system. Because all the internal surfaces of interest transition smoothly into one another, you can efficiently select them using the Tangent Faces selection method option.

  Thermal Constraints (Home tab→Loads and Conditions group→ Constraint Type list)

  • Type

    Fixed Temperature

  • Method (Top Border bar)

    Tangent Faces

  •  

  • 227 faces are selected.

  •  

     

  •   (Temperature)

  •   New Field→Formula

  •  

     

  • Independent

    Cylindrical

  • Spatial Map

  • Type

    Cylindrical

  • Specify CSYS

      Inferred

  •  

  •  

     

  •   the temperature row

  • Expressions (box under the table)

    150*(1+cos(ug_var("theta")))+300-abs((ug_var("z")/1[mm])-45)
  • Tip:

    You can copy the expression above and paste it into the box.

  • Accept Edit

  • The expression is written in dimensionless form. The software automatically interprets the numerical results of the expression as having the units of the dependent variable. The dependent variable in this case is °C. Because z is in millimeters, it is made dimensionless by dividing by 1[mm]. The cosine of theta is already dimensionless.

    Note:

    To write the expression in dimensional form, you must ensure the units resulting from evaluating the expression are identical to the units of the dependent variable. For example, you can write the above expression in dimensional form as:

    150[C]*(1+cos(ug_var(“theta”)))+300[C]-abs((ug_var(“z”)*1[C]/1[mm])-45[C])

  • OK

     both dialog boxes

  Save

4: Plot the temperature variation

  Simulation Navigator

  • Fields

  • Temperature

    Plot (XY)

  • Variable

    theta

  • Minimum

    0.0

  • Maximum

    90.0

  • Number of points

    1001

  • Apply

     

  •  

      Create New Window (Viewport dialog box)

  •   Graph Window 1

  • Variable

    z

  • Minimum

    –200.0

  • Maximum

    200.0

  • Number of points

    1001

  • OK

     

  •   Create New Window (Viewport dialog box)

  •   Graph Window 1

5: Solve the thermal model

  Simulation Navigator

  •   Thermal Solution

      Solve

  • OK

     

  • Wait until the solve is complete.

  • No

     Review Results dialog box

  •   the Information window

  • Cancel

     Analysis Job Monitor dialog box

6: Display the thermal results

  Simulation Navigator

  •   Thermal Solution→Results

  • Thermal

 

Post Processing Navigator

  •   Thermal Solution→Thermal→Temperature - Nodal

  •   Scalar

After you have viewed the thermal results, return to the model display.

  Return to Home (Context group)

At this point, you could create a structural solution and use the thermal results in the structural model to calculate thermal stresses.

  Save

File

  • Close→All Parts