Four Steps:

NOTE: If you are using a natural environment (weather), click here for instructions.

1. Create curves for any time-varying parameters in your system, such as heat rates, temperature curves, or convection rates.
2. Specify start and end times for your analysis.
3. Specify step size and how often to save results.
4. Choose an initial starting temperature for all part(s) or choose to seed the transient run with a steady-state analysis at the first time step.

To create the curves go to the Editor>Curves tab.

Step 1: Create curves for any time-varying parameters in your system.

Go to the Edit>Curves Tab. Select the type of curve you wish to create in the pull-down menu. Click the ADD button and enter a name for the curve. Input the time-varying data points. If the solution time exceeds the time of the last data point in the curve, ThermoAnalytics software will hold the final value of the curve for all remaining time steps. Create all necessary input curves, or import curves from an ASCII file or from an existing TDF file. (TDF is the default file extension for ThermoAnalytics model files.)

Step 2: Specify start and end times for your analysis.

Go to the Analyze>Params Tab
In the Solutions Parameters box, enter your desired start and end times for your simulation. The default start and end times are "0." When the start and end times are the same, the analysis will be a steady-state analysis. This allows you to conduct a steady-state analysis under the conditions defined at any point in time. For example, you could define a heat rate over a 10-minute time span and set the start and end times to 5.0 minutes. The analysis would be a steady-state analysis under the conditions defined at T=5.0 minutes. Our software will linearly interpolate values for time steps between data points.

Step 3: Specify step size and how often to save results.

IMPORTANT: Choose a step size that is appropriate for your needs. The default is 0.5 minutes. If you run a large model (say, 100,000 elements) and save results for 100 timesteps, you will have a very, very large file of results. Therefore, if you choose a short time step, you may wish to store results only every X number of time steps. Just below the Solution Parameters box, you can specify "Save results every X time steps."

For a quick run, you may wish to select a high tolerance value, allowing a faster run time with less accurate results. For example, choose Tolerance and set the tolerance to 0.1C or 0.1F. The results will not be highly accurate, but the run time will be shorter.

Step 4: Define the initial conditions.
In the Editor>Parts tab, you can define the starting temperature for the front and back of all parts. The default initial temperature setting is Seed SS. This means that the whole modeling system will be allowed to come to equilibrium with all T=0 inputs (including weather, if a natural environment is chosen) before moving to the first time step.

To define initial temperatures for each part individually, select each part in turn and select Bypass SS. Enter the desired starting temperature for the FRONT and BACK sides of each part. The default is 20C. Note that if you have a highly conductive part and you choose different Front and Back temperatures, the simulation may "bounce" energy between the two thermal nodes.

To set all of the initial temperatures to a single value, select all of the parts using the Parts List. From the menu bar, select Window>Parts List (in Version 5 or 6, it is found under View>Parts List). If you wish to exclude a few parts, hold the CONTROL key and click on the names of those parts. All selected parts' names will be highlighted in blue, and the parts' geometry will highlight in the graphics window.

Click the "Select All Parts" button. Click "Bypass SS" and enter a value. This will affect all parts, and the BACK value will default to the value you entered. If the Current Part is a fluid or an assigned temperature part, and you do not see the Seed SS or Bypass SS, hold the CONTROL Key and click TWICE on a "calculated" part that has geometry in the Parts List. This procedure will make that part current, and the Front and Back tabs will be enabled.

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