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Post by Deleted on Apr 10, 2013 5:11:46 GMT -8
Simulation of heat transfer through 5cm fire brick and 7.5cm adobe. Without convection as Energy2D cannot handle such complex simulations. Energy2D needed to run energy.concord.org/energy2d/energy2d.jarAttachments:
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Post by Deleted on Apr 14, 2013 7:34:58 GMT -8
Simulation of a bell. Attachments:
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Post by Donkey on Apr 14, 2013 23:24:13 GMT -8
Very cool. Now I need to learn how to use the thing to build something that works properly and makes sense.
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Post by Deleted on Apr 15, 2013 2:33:53 GMT -8
Very cool. Now I need to learn how to use the thing to build something that works properly and makes sense. Energy2D is simple and not very powerful. OpenFoam could simulate a complete RHM, with bells and whistles like a Peter chanel. It can even simulate fuel burning with a chemical reactor simulation. But OpenFoam is a very powerful and very complicated tool for scientists and engineers. Unfortunately there is no GUI. Commercial simulators are very expensive. Could be something for a student looking for serious scientific work.
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Post by Deleted on Apr 18, 2013 7:17:34 GMT -8
I wrote to the people at "energy.concord.org" and made some suggestions to Energy2D and got the following answer.
Von: "Charles Xie" <qxie@concord.org> Betreff: Re: Energy2D We are hoping to include phase change and chemical reaction (including combustion) using Stefan's boundary condition. It requires a lot of math work that we still have to plow through. But I think it will come eventually.
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Post by Deleted on Apr 22, 2013 6:59:46 GMT -8
Simulation of a double bell. Attachments:
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Post by Deleted on Apr 22, 2013 7:07:03 GMT -8
Simulation of a barrel. Attachments:
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Post by Deleted on Apr 24, 2013 5:24:54 GMT -8
Simulation with venturi. Attachments:
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Post by Deleted on Apr 24, 2013 5:25:36 GMT -8
Another simulation with venturi. Attachments:
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Post by pinhead on Apr 24, 2013 8:07:18 GMT -8
These are some neat simulations which mostly confirm what I thought was happening inside the bell. In the double-bell simulation, things get really interesting if you slow down the incoming airspeed to about 0.15 m/s. I also found that the simulations seem to be more accurate if you "enclose" the entire screen inside a "box" with extremely low thermal conductivity (while "venting" the bell inside this space). It also seems that this simulator isn't calculating mass flow, as you can have an air inlet without an outlet. Under those circumstances you can really see the convection taking place within both bells. I would have thought, though, that the incoming air would immediately rise when entering the bell. However the simulation shows that convection within each bell tends to "hold down" the incoming air until it gets toward the end of the bell. The attached "double bell" simulation seems to be a decently-accurate rendition of the bell system that I'm currently using in my RMH. Attachments:
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Post by Deleted on Apr 24, 2013 9:10:23 GMT -8
pinhead, right click in the blue area and then on Properties. In the popup window click on Baudary. Then you can set the Thermal and Mass Boundaries. Set the Thermal boundary to Neumann (constant heat flux) and enter low values. The Mass boundaries can be set to reflect or through. Attachments:
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Post by pinhead on Apr 24, 2013 10:03:13 GMT -8
Without convection as Energy2D cannot handle such complex simulations. If Energy2D isn't showing convection, what exactly are the simulations showing? pinhead, right click in the blue area and then on Properties. In the popup window click on Baudary. Then you can set the Thermal and Mass Boundaries. Set the Thermal boundary to Neumann (constant heat flux) and enter low values. The Mass boundaries can be set to reflect or through. Thanks! Now I can set the system to vent to the outside world, while simulating a well-insulated building around the two bells.
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Post by Deleted on Apr 24, 2013 10:17:13 GMT -8
Without convection as Energy2D cannot handle such complex simulations. If Energy2D isn't showing convection, what exactly are the simulations showing? It can show convection, but with short time steps. Wit much shorter time stepp there would not be much to see in this particular simulation. Another variation of your double bell. Attachments:
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Post by Deleted on Apr 27, 2013 5:32:29 GMT -8
Another stab on the venturi. The real wind speed would be on average 5 times and up to 10 times higher. Currently Energy2D cannot simulate that. Attachments:
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Post by Deleted on Apr 27, 2013 7:19:07 GMT -8
This one allows the highest wind speed, which means that it has the least friction, at least in the mathematical model. Attachments:
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