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Time Dependent Solar Radiation Study

Question asked by Timothy Jordan on Jul 30, 2014
Latest reply on Aug 6, 2014 by Jared Conway

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I'm looking to analyze a fixture that will be mounted in ground and is subjected to solar radiation. I'd like to see the temperature of the fixture over time, and how it changes depending on time of day. In Solidworks Flow Simulation there is an option to select time of day and location for solar radiation. Is it possible to do a time dependent study, where the solar radiation setting for time of day is automatically incremented? Or is the best method to do several steady-state analyses, manually inputting different times of day? Thank you.

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Jared Conway Jul 30, 2014 4:23 PM
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you can definitely do the steady state option
have you tried switching to a transietn analysis and seeing if the components of solar radiation have "FX" indicating that they could be changed with time?
you could also use a parametric study to just rotate your part instead of changing the parameters of the solar radiation if you go with the steady state option
i'd recommend putting this in the flow sim category
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David Hensel Aug 4, 2014 10:02 AM
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SOLIDWORKS Flow Simulation will properly apply Solar Radiation when used in a time-dependent study. Specify the start time in the "Solar Radiation" settings, and the duration of the study in the "Time Dependent" settings.

For example, you can specify a time of 6:00 and duration of 21600 seconds, which would simulate a "sunrise" until 12:00. Alternatively, you could use 14:00 with 3600 seconds for an hour in the afternoon. etc. It is important to consider the initial conditions used though, which will be considerably different between these two (since it's warmer at 2 pm than 6 am).

You can refer to "Environment and Solar Radiation" in the Technical Reference for details about the implementation, including how the incident solar radiation is prescribed.
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- Carel Kriek @ David Hensel on Aug 4, 2014 3:54 PM
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  Additional to what David has described you can choose the periodical saving option. During post processing it is a matter of loading the relevant result file to see results corresponding to a specific time.
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- Jared Conway @ David Hensel on Aug 4, 2014 11:51 PM
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  good call david, glad someone could confirm. was wondering where the OP was getting stuck. probably missing the time dependent option? I guess we'll have to wait to find out
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- Timothy Jordan @ David Hensel on Aug 5, 2014 9:45 AM
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  For "Time Dependent", I do not see the option for any settings such as input for duration of study (see image below). Should this be done in "Calculation Control Options"?
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  - Carel Kriek @ Timothy Jordan on Aug 5, 2014 10:04 AM
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    Timothy, yes you need to set the time duration in Calculation Control Options - under "Finish". (See Maximum Physical Time). Also undo the Goals Criteria so that the calculation will not be accidentally stopped by a goal criterium (you want it to finish at the maximum physical time that you choose). Then you can go to "Saving" also under Calculation Control Options and set up a periodic savings schedule to create result files every so many (you choose) seconds or minutes. You can load these result files to look at results vs. physical time.
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  - David Hensel @ Timothy Jordan on Aug 5, 2014 5:20 PM
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    Did you already run your simulation? It seems these settings are only available on the general settings/wizard before the study is run. I'm not sure what causes these options to be "removed" to calculation control options after the simulation is run. Edit: This is shown only in the Wizard, not the General Settings. The wizard is providing additional assistance for setting up the project.
    
    What do you think about the existing behavior, where the controls are moved to "Calculation Control Options" after running the simulation?
    What do you think of specifying these values in the Wizard vs. in Calculation Control options? Do you use the wizard?
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    - Carel Kriek @ David Hensel on Aug 5, 2014 4:43 PM
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      David, I hardly ever use the wizard to set up simulation studies. I use the general settings directly after creating a new project. Then I use Calculation Control Options before running the project so I cannot answer your question in this regard. Jared, can you help here?
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      - David Hensel @ Carel Kriek on Aug 5, 2014 5:17 PM
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        So if I'm understanding this correctly, when you create a time-dependent study you are already planning on going to Calculation Control Options to further specify your project setup? In this case, it would not be important to specify these values on the General Settings, since they can be further specified in another location where you have additional control over the solver.
        
        I ask this, because it is important to understand how these cases are typically set up. I know how I'd set this up, but that is possibly different from yours, Jared's and Timothy's workflow. I usually start with the wizard, to set up units, materials etc.
        
        To be honest, I find it confusing that there is an inconsistency between the General Settings option for "Time Dependent" and the one shown in the Wizard, where it appears nearly the same UI but also allows you to specify some more information (from Calculation Control).
        
        As always, if you have ideas for future software improvements, please submit as an Enhancement Request through the Customer Portal (requires subscription service).
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        Jared Conway @ David Hensel on Aug 6, 2014 12:03 AM
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        I use the wizard almost exclusively because that is the method that we teach in our training and also our mentoring.
        
        but in mentoring, we specifically go over the fact that the wizard is a "special" interface that once completed splits into initial mesh and calc control options and then show the difference.
        
        there should be enhancement requests in the system to condense everything into a unified input system but they've been in there for a long time so I doubt they are high on the priorities.
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Nicholas Luyster Aug 5, 2014 6:45 PM
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Hi Timothy,

Unless this fixture is huge and has a high specific heat, this fixture will not fluctuate in temperature fast enough to justify a time dependent simulation. Time dependent studies should be reserved for cases where the thermal load is brought on relatively fast. As an example: you would run a time dependent study if you flicked on a light switch and you wanted to study how the temperature of the bulb was affected over the course of the first 15 minutes.

Unless this fixture holds onto a lot of heat, you should make the assumption that over the course of an hour the sun does not change fast enough to justify time dependency.

Instead, create several steady state simulations for each time of the day you're interested in. I suggest automating this through a parametric study if possible.

All the best,

Nick
SolidWorks Simulation Training
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- Jared Conway @ Nicholas Luyster on Aug 6, 2014 12:04 AM
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  probably depends on his goals
  could well be that he wants to show the effect that you describe is actually the case
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