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Adequate timestep selection for multidomain problem

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Old   November 27, 2010, 15:37
Default Adequate timestep selection for multidomain problem
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I'm setting up a multidomain (solid and fluid) transient simulation of a furnace (involving combustion) where I wanna know how much time is needed to get certain temperature in part of a solid domain (according to the experimental data is 4 hours).

I selected a timestep of the order of 1e-04 as the initial timestep and a factor of 10 to increase it, but after severeal timesteps calculations this timestep hasn't been increased yet (after 30 timesteps aprox.).

So my question is, how can i achieve the result i desire using a higher timesteps with a good phisical accuracy, because if the initial timestep doesn't increase i will never get the Total time of the simulation (aprox. 4 hours).

Thanks in advance.
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Old   November 27, 2010, 20:58
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What are you using as your adaptive time step critereon?
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Old   November 27, 2010, 21:20
Default Adequate timestep selection for multidomain problem
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I'm using the Number of Coefficient Loops method....

I tried switching to a timestep list with the number and the value of timesteps over my whole simulation and combustion never started...I'm using EDM and I don't know why combustion doesn't starts, as a solution I included a source point with the double of the activation energy as the source value with any satisfactory result...

Any advice on my problem will be very welcome...thanks in advance ghorrocks...
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Old   November 28, 2010, 15:05
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always the same misunderstandings . First I would use "pure" EDM. Check the model equations in order to understand why pure EDM for premixed flames cannot be ignited by temperature or enthalpy.
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Old   November 28, 2010, 15:24
Default Adequate timestep selection for multidomain problem
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Yes....well i have already solved that isssue turning -1. the B coefficient (producto limiter), i had a value of 0.5 to control combustion
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Old   November 28, 2010, 17:50
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For single phase simulations you usually aim to get 2-5 or 3-5 coeff loops per iteration. For multiphase and combustion you will probably have to increase it, maybe 5-10 loops per timestep. But you might want to have some fine and constant time steps when you start the combustion.
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Old   November 28, 2010, 18:50
Default Adequate timestep selection for multidomain problem
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Thanks for the help i'll struggle to get this done efficiently
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