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Flipping or rotating geometry during time-dependent evaluation

Posted 04.02.2021, 04:02 GMT-5 Heat Transfer & Phase Change, Geometry 4 Replies

Emil Rasmussen
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Hi

I am trying to model and simulate the cooking process of frying a steak on a frying pan. I need some way of simulating the flipping of the meat after said time. How would I go about rotating my geometry (near) instantaneously?

Thanks Emil

4 Replies Last Post 09.02.2021, 11:47 GMT-5
Edgar J. Kaiser Certified Consultant
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Posted: 4 years ago 04.02.2021, 06:27 GMT-5

Emil,

nice project with high real world significance ;-).

My suggestion is not to rotate the geometry but switch the boundary conditions on both sides of the meat. You will need to apply some ramping though, time dependent solvers don't like (near) instantaneous changes.

Cheers Edgar

-------------------
Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
Emil, nice project with high real world significance ;-). My suggestion is not to rotate the geometry but switch the boundary conditions on both sides of the meat. You will need to apply some ramping though, time dependent solvers don't like (near) instantaneous changes. Cheers Edgar
Emil Rasmussen
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Posted: 4 years ago 09.02.2021, 03:47 GMT-5

Dear Mr. Kaiser

Thanks for your reply, that solution seems very viable to me! This is my first time working in COMSOL, so I apologize for my little knowledge. What function within the software should I utilize to change boundary conditions during time dependent solving, ie. set a "flip" of boundary conditions after 30 secs?

Dear Mr. Kaiser Thanks for your reply, that solution seems very viable to me! This is my first time working in COMSOL, so I apologize for my little knowledge. What function within the software should I utilize to change boundary conditions during time dependent solving, ie. set a "flip" of boundary conditions after 30 secs?
Magnus Ringh COMSOL Employee

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Posted: 4 years ago 09.02.2021, 09:46 GMT-5

Hi,

If both conditions are different temperature conditions, then an expression like

(t<30[s])*225[degC]+(t>=30[s])*23[degC]

(and vice versa for the other side) would flip the temperature conditions from the hot side (225 degrees C, for example) to the surrounding temperature (23 degrees C , for examplel) after 30 seconds. The logical operators provide a factor that is 0 when false and 1 when true. There are also operators and a Step function that you can use to get a smoother transition. See the section called "Specifying Discontinuous Functions" in the user documentation.

Best regards, Magnus Ringh

Hi, If both conditions are different temperature conditions, then an expression like `(t=30[s])*23[degC]` (and vice versa for the other side) would flip the temperature conditions from the hot side (225 degrees C, for example) to the surrounding temperature (23 degrees C , for examplel) after 30 seconds. The logical operators provide a factor that is 0 when false and 1 when true. There are also operators and a Step function that you can use to get a smoother transition. See the section called "Specifying Discontinuous Functions" in the user documentation. Best regards, Magnus Ringh
Emil Rasmussen
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Posted: 4 years ago 09.02.2021, 11:47 GMT-5

Hi,

Thank you very much for that reply. I will try out those types of logic functions. I appreciate the fast response!

Hi, Thank you very much for that reply. I will try out those types of logic functions. I appreciate the fast response!

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