These notes are a supplement to the PAT 312 Patran Thermal class and are intended to answer the most commonly asked Patran Thermal questions.

You will be specifying the temperature variation as a Non Spatial Field as follows:

Select the Fields Button.

Set the Action-Object-Method to Create-Non Spatial-General respectively.

Enter a field name that describes this boundary condition in the Field Name databox.

Select the Input Data button.

To enter a table of time vs. temperature data, set the Select Function Term to mfid_indx_linr_tabl which stands for microfunction of indexed linear table.

Enter a Micro Function ID (MFID) to a number that you will reference in the template.dat MACRO template. You can modify the default number to a number that matches the MACRO number you will use in the Loads/BCs form.

Fill out the spreadsheet of Independent Variable (time) vs. Dependent Variable (temperature) data. Select OK and Apply.

Select the Loads/BCs Button.

Set the Action-Object-Type to Create-Temperature(PThermal)-Nodal.

Set the Option to Variable.

Select the Input Data button.

Input Temperature Scale Factor of “1” and enter a Template ID of 1 for your first varying temperature boundary condition.

Enter the desired node(s) in the Select Application Region subform and select Apply.

In the same directory where the database exists, create a file called template.dat.apnd. All information in this file will be copied to the template.dat file in the job name subdirectory when the job has been submitted.

Enter the following information into the template.dat.apnd file:

MACRO 1 1 0 0 1.0

1

where the “1” following the keyword MACRO refers to the template ID that you entered in the Loads/BCs Input Data form. The “1.0” is a scale factor for the temperatures and the “1” on the second line refers to the microfunction ID that you specified in the Micro Function ID (MFID) databox in the Fields form.

If you have two time varying boundary conditions, then you would add two additional lines as follows:

MACRO 2 1 0 0 1.0

2

Note that comment cards in this file begin with the character “*”.

See class problem number 5 for an example of this process.

The heat application is very similar to the “Temperature Varying with Time” application described above.

Variable heat input can be in the form of nodal heat source, volumetric heat flux, and heat flux.

You will be specifying the heat variation as a Non Spatial Field as follows:

Select the Fields Button.

Set the Action-Object-Method to Create-Non Spatial-General respectively.

Enter a field name that describes this boundary condition in the Field Name databox.

Select the Input Data button.

To enter a table of time vs. temperature data, set the Select Function Term to mfid_linr_indx_table which stands for microfunction of linear indexed table.

Enter a Micro Function ID (MFID) to a number that you will reference in the template.dat.apnd MACRO template. You can modify the default number to a number (3 for example) that matches the MACRO number you will use in the Loads/BCs form.

Fill out the spreadsheet of Independent Variable (time) vs. Dependent Variable (heat) data.

Select the Loads/BCs Button.

Set the Action-Object-Type to either

Set the Option menu to either Nodal Source, Fluxes, or Volumetric Generation.

Select the Target Element Type as appropriate.

Select the Input Data button.

Input Loads/BC Scale Factor “1” and enter a Template ID of 3 (arbitrary) for a varying heat boundary condition.

Enter the desired node(s) (or element(s) for Flux and Volumetric Generation) in the Select Application Region subform and select Apply.

In the same directory where the database exists, create (or open) a file called template.dat.apnd. All information in this file will be copied to the template.dat file in the job name subdirectory when the job has been submitted.

Enter the following information into the template.dat.apnd file:

MACRO 3 1 0 0 1.0

3

where the “3” following the keyword MACRO refers to the template ID that you entered in the Loads/BCs Input Data form. The “1.0” is a scale factor for the temperatures and the “3” on the second line refers to the microfunction ID that you specified in the Micro Function ID (MFID) databox in the Fields form.

If you have two time varying boundary conditions, then you would add two additional lines as follows:

MACRO 4 1 0 0 1.0

4

Note that comment cards in this file begin with the character “*”.

To apply a known amount of heat to a region of elements, use the Shareware pull down menu, and select Total Heat. Use the Per Area option if the heat is applied evenly over the element faces and use Per Volume if the heat is to be spread out evenly throughout the solid element (Tet/ Wedge/ Hex).

Select the Loads/BCs button and set the Action-Object-Type to Create-Convection(PThermal)-Element Uniform. Set the Option to Use Correlations. This option give the user the choice of using correlations (or a table as in this case).

Enter a New Set Name that describes this boundary condition. Set the Target Element Type to 2D for plate elements or 3D for solid element faces.

Leave the Loads/BC Set Scale Factor at 1 (this is not a convection coefficient scale factor!). Leave the Convection Coefficient blank. This is a scale factor to the table of convection coefficients vs. time or temperature. Input a Convection Template ID value (1 for example). This is a pointer to the template.dat.apnd file. Enter the Fluid Node ID and select OK. Select Application Region, select the FEM button and select the desired elements. Select OK & then Apply.

In the same directory where the database exists, create (or open) a file called template.dat.apnd. All information in this file will be copied to the template.dat file in the job name subdirectory when the job has been submitted.

Enter the following information into the template.dat.apnd file:

Note that comment cards in this file begin with the character “*”.

The “CONV” is a keyword for convection templates. The first “1” is the template id supplied in the Loads/BCs Input Data form. “29” denotes the convection configuration for time or temperature varying convection as described in the documentation. “0” denotes the number of geometric properties (GPs) supplied by this template, and the last “1” is the number of MPIDs for the configuration. This MPID is given on the next line & is arbitrarily given the number “5001”.

The number of GP values defined by the template is zero in this case because the correlation only requires the nodal subarea which is supplied by Patran and PATQ during the translation process.

In the same directory where the database and template.dat.apnd file exist, create (or open) a file called “mat.dat.apnd”. All information in this file will be copied to the “mat.dat” file in the job name subdirectory when the job has been submitted.

Enter the table into the “mat.dat.apnd” file as follows:

The MPID is a keyword for material property id. The “5001” refers back to the “5001” given in the template.dat.apnd file. “ITABLE” denotes that this is an indexed table which means that Patran Thermal starts the search in this table where it left off in the last time step and is therefore faster than the “TABLE”.

Any input other than “MDATA” or “/” after an MPID keyword is assumed to be a comment. For this example, the “Convection Coefficient (Btu/hr-ft^2-F) as a function of Time (seconds)” is a comment that describes this table.

The “/” is required at the end of each MPID input.

To input this table of convection coefficient as a function of temperature, use the keywords “Fahrenheit,” “Rankine”, “Celsius”, or “Kelvin” in place of the keyword “Time”.

Select the Loads/BCs button and set the Action-Object-Type to Create-Convection(PThermal)-Element Uniform. Set the Option to Between Regions. When selecting the Application Region, set the Order to Closest Approach. To create contact conductance between two geometric solid faces that contact each other in the Patran model, both application regions should be element based (such as setting Region 2 to 3D). If Nodal is selected for Region 2, and a surface or face of a solid geometric entity is selected, Patran will fill the listboxes with the nodes from both contacting faces even if only one face is selected (an error will flag this when selecting the Analysis Apply button).

PCL that creates the radiation boundary condition and eliminates the need for editing the “template.dat.apnd” file for viewfactor templates exists and will be included on the Shareware pulldown menu as described above.

or

Select the Loads/BCs button and set the Action-Object-Type to Create-Radiation (PThermal)-Element Uniform. Set the Option to View Factors

Enter a New Set Name that describes this boundary condition. Set the Target Element Type to 2D for plate elements or 3D for solid element faces.

Select the Input Data button.

Leave the Loads/BC Set Scale Factor at 1 (this is not a viewfactor scale factor!). Input a viewfactor Template ID value (1 for example). This is a pointer to the template.dat.apnd file. Leave the Participating Media Node databox empty. If your model is not completely enclosed, enter the ambient node into the Ambient Node Id databox. Viewfactors that do not see any portion of your model will see the temperature of this node (fixed or variable). The viewfactor code will not attempt to calculate viewfactors for all elements with the same Convex Set Id (any integer number). The Obstruction Flag databox is another CPU saving feature that can be left empty. The default viewfactor direction will be applied in the element normal direction. Under the Finite Elements Verify-Element-Normal form, arrows can be displayed in the element normal direction. If the opposite direction is desired, Enter “1” in the Top/Bottom Flag databox to apply the viewfactor boundary condition in the bottom direction. In order to have radiation off of both faces of a plate element, two viewfactor applications must be applied, one with the Top/Bottom Flag empty (or set to “0”), and the other with the flag set to “1”. The last databox is the Enclosure Id. Only viewfactors with the same Enclosure Id have the possibility of seeing each other.

Select Application Region, select the FEM button and select the desired elements. Select OK & then Apply.

In the same directory where the database exists, create (or open) a file called template.dat.apnd. All information in this file will be copied to the template.dat file in the job name subdirectory when the job has been submitted.

Enter the following information into the template.dat.apnd file:

Note that comment cards in this file begin with the character “*”

“VFAC” is a keyword to signify viewfactor template. The first “1” is the template id that you supplied in the Loads/BCs Input Data form. Assuming you are not performing spectral analysis (emissivity varying with wavelength), then the"# of bands” is zero.

The second line (of non-comment input) starts with the emissivity. This is the only required input for this line. The “collapse” flag at the end of this line is beneficial in reducing the size of your radiation network by up to a factor of 16. The “tau” is the transmissivity and is set to “1” unless you have a participating media. The “emis. MPID” is the material property ID for variable emissivity. Set this to zero for fixed emissivity. The same is true for “tau MPID”. Since this is not a spectral problem, “band1”, “band2”, and “kflag” are set to “0”. All element viewfactors with the same “collapse” flag ID will be condensed.

If you wish to use the materials from the Patran Thermal library, use the Shareware-Thermal Tools pull down menu item P/Thermal Materials List. Input the name of the material of interest, such as “alu” to get a listing of all materials in the Patran Thermal material library that contain the characters “alu”. To use this material in your model, you may skip the Materials form entirely and input this material ID in the Element Properties, Input Data form in the Material listbox

To input your own materials that vary with temperature, Select the Fields button from the main menu, and set the Action-Object-Method to Create Material Property General. Enter a descriptive name for this field, and select Input Data. Select the desired option for you field. For a table, select mpid_indx_linr_tabl. Now you can enter a table of temperature versus material property (i.e. conductivity, etc.). Be sure to select Apply after completing input for each table

This information will get written to your jobname directory into a new mat.dat file when you submit your job.

All other material properties can be input from the Materials form selected from the main form.

For 3 dimensional models (vary in x, y, and z), be sure to use the Action-Dimension-Type of Create-2D-Shell for plate elements (quads or trias). Release 1.4 no longer requires the input of four thickness values for each corner.

For the case where a model is 2 dimensional (all of model is constructed in x-y plane) and is assumed to have unit depth thickness in the z-direction, use the Action-Dimension-Type of Create-2D-Thermal 2D for plate elements. Since unit depth is assumed, no input of element thickness is input.

Load cases are not supported for Patran Thermal. Create all of the loads and boundary conditions in the default loadcase.

Select Analysis from the main menu. Be sure to correctly specify the model dimensionality in the Solution Type menu. 2D assumes that all of your model is in the x-y plane and that you have unit depth in the z direction. For models which have bar elements with cross sectional area, plate elements with thickness, and/or solid elements, use the 3D selection. See Element Properties, 53.

If you are resubmitting you analysis, and you wish to reuse the settings you had from your last run, select a previous job from the Available Jobs listbox in the Analysis form. You can then modify any setting you wish before you select the Apply button.

To verify that your job submittal was successful, examine the patq.msg files and look for error messages. If you are running a viewfactor job, you can check the status by examining the vf.msg message file.

Note that the shareware pull down menu has a Translation Status option that examines the contents of the patq.msg file for you.

In the jobname directory, enter the command qstat or qstat -b. qstat will give the status of your job while (and after) it's running. Check to make sure that the temperature change between iterations is decreasing and is approaching 1.e-05 for convergence with the default parameters. If your model has not converged after 1999 iterations (the default maximum allowable for steady state as displayed by qstat), verify that your material properties are correct. Note that the convergence criteria is based on the slope of the model convergence and not a simple iterative delta in temperature.

The Patran Thermal Tools pulldown menu has a Thermal Convergence Status option that makes x-y plots of the convergence status. Be sure to use the Clear button when finished viewing these plots to clear the windows for the next time you wish to check the status.

At the UNIX window in the jobname directory, enter the UNIX command:

% ls qout*

The highest version of qout.dat.* is the most recent output file. Verify that the total heat you intended to input to the model matches the value of TOTAL HEAT SOURCE INPUT ENERGY displayed from the UNIX command:

% grep HEAT qout.dat.#

where # is the highest value of qout.dat in your directory.

From the same “grep” command given above, be sure that the value of SYSTEM HEAT BALANCE is small relative to the TOTAL HEAT SOURCE INPUT ENERGY (less than 1% is a common rule of thumb) for steady state analyses.

Before submitting your job, select Output Requests from the Analysis form. Select the Nodal Results Type button, and select all 8 of the output options. When you post process your results, you will have the net nodal heat flux at each node. If you create a new group without the boundary nodes, your fringe plot should be very close to zero for all nodes. If all of you values are exactly 0, then you probably did not set the output requests form to include all eight output options. You can resubmit the job for one iteration to get a new result file.

From the jobname directory, enter the UNIX command:

% ls -rt nr*

to get a listing of the nodal result files in reverse time order. The last file should be read in for a steady state analysis. This command is important as the following example illustrates.

Run 1: Material properties were input in meters instead of millimeters for one of the materials. The job never converges and give output files every 500 iterations; nr0.nrf.1, nr1.nrf.1, nr2.nrf.1, nr3.nrf.1.

Run 2: Material property corrected and job converges in 27 iterations resulting in nr0.nrf.2.

Then the Analysis form is selected and the Action is set to Read Results, Select Results File. After selecting the jobname directory, which will filter on the nr* files, the last one listed is nr3.nrf.1 (from UNIX alphanumeric sorting). However, the nr0.nrf.2 file should be selected if the most recent result is desired.

Next, select the Select Rslt Template File button, scroll towards the bottom and pick the last pthermal result template (pthermal_nod_T.res_tmpl) and select apply. This result template allows for all 8 result values that may have optionally been selected within the Output Requests-Nodal Results File Format form before the job was submitted. If only temperature was requested in the output files (default) then the remaining values of net nodal heat flux, etc. will be zero.

Select Results and display the fringe plot.