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Old   May 4, 2015, 22:04
Default Steady/ Transient Calculations
S. Morichika
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I am using FLUENT to simulate particle transport. I need to simulate steady case for DPM. I read the user manual and the manual says,

" In the Discrete Phase Model Dialog Box you have the option of choosing whether you want to treat the particles in an unsteady or a steady fashion. This option can be chosen independent of the settings for the solver. Thus, you can perform steady state trajectory simulations even when selecting a transient solver for numerical reasons. You can also specify unsteady particle tracking when solving the steady continuous phase equations. This can be used to improve numerical stability for very large particle source terms or simply for postprocessing purposes. Whenever you enable a breakup or collision model to simulate sprays, the Unsteady Particle Tracking will be switched on automatically.When Unsteady Particle Tracking is enabled, several new options appear. If steady state equations are solved for the continuous phase, you simply enter the Particle Time Step Size and the Number of Time Steps, thus tracking particles every time a DPM iteration is conducted. When you increase the Number of Time Steps, the droplets penetrate the domain faster.When solving unsteady equations for the continuous phase, you must decide whether you want to use Fluid Flow Time Step to inject the particles, or whether you prefer a Particle Time Step Size independent of the Fluid Flow Time Step. With the latter option, you can use the Discrete Phase Model in combination with changes in the time step for the continuous equations, as it is done when using adaptive flow time stepping.

If you do not use Fluid Flow Time Step, you must decide when to inject the particles for a new time step. You can either Inject Particles at Particle Time Step or at the Fluid Flow Time Step. In any case, the particles will always be tracked in such a way that they coincide with the flow time of the continuous flow solver."

I need to simulate steady case. My question is, If I select "Transient" from the general tab and then set the particle time step size from the DPM tab, is it ok? As the user manual says,you can perform steady state trajectory simulations even when selecting a transient solver for numerical reasons.

I am little bit confused about it. Could anyone have clear idea regarding this problem.

Thank you in advance.

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dpm, fluent, steady, transient

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