View Issue Details
| ID | Project | Category | View Status | Date Submitted | Last Update |
|---|---|---|---|---|---|
| 0004133 | OpenFOAM | Bug | public | 2024-08-12 10:09 | 2024-08-13 10:10 |
| Reporter | rcarneiro | Assigned To | will | ||
| Priority | normal | Severity | minor | Reproducibility | have not tried |
| Status | resolved | Resolution | fixed | ||
| Product Version | 12 | ||||
| Fixed in Version | dev | ||||
| Summary | 0004133: Brownian force - Lagrangian | ||||
| Description | Hello everyone, I want to report what seems to be an error in calculating particle acceleration due to Brownian force when turbulence is true. From the code below, we can see that the units of 'f' are [(m/s^2) K] indicating that something is incorrect. Could you please double-check this equation? // Boltzmann constant const scalar kb = physicoChemical::k.value(); scalar f = 0; if (turbulence_) { const label celli = p.cell(); const volScalarField& k = *kPtr_; const scalar kc = k[celli]; const scalar Dp = kb*Tc*cc/(3*mathematical::pi*muc*dp); f = sqrt(2.0*sqr(kc)*sqr(Tc)/(Dp*dt)); } Furthermore, it is not fully clear to me why, in the presence of turbulence, the calculation of the Brownian force is different from when there is no turbulence. Is there any publication mentioning this? Thank you for your time. Regards, Rui | ||||
| Tags | No tags attached. | ||||
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I agree with your dimensional analysis. The implementation must be wrong. Whilst I can find a similar expression for Dp in the reference, I can't find an expression for how that is turned into a force, or anything depending on the turbulent kinetic energy. So, I have removed this part of the model. The non-turbulent part, by contrast, appears to be dimensionally consistent and matches the reference. https://github.com/OpenFOAM/OpenFOAM-dev/commit/9ca88df33f043621af7d127180a96a4bb88ac21c |
