View Issue Details
| ID | Project | Category | View Status | Date Submitted | Last Update |
|---|---|---|---|---|---|
| 0000277 | OpenFOAM | Bug | public | 2011-08-16 05:56 | 2011-08-16 09:20 |
| Reporter | alundilong | Assigned To | henry | ||
| Priority | normal | Severity | major | Reproducibility | always |
| Status | closed | Resolution | fixed | ||
| Platform | Linux | OS | Ubuntu | OS Version | 10.04 |
| Summary | 0000277: mass diffusivity is missing in species equation | ||||
| Description | Taking a look at the species equation, the coefficient in laplacian equation should be mass diffusivity (Dt) instead of effective viscosity (μt). see links below, as shown in equation 14. http://www.rpgroup.caltech.edu/~natsirt/aph162/diffusion.pdf However, this is written in YEqn.H fvm::ddt(rho, Yi) + mvConvection->fvmDiv(phi, Yi) - fvm::laplacian(turbulence->muEff(), Yi) == dieselSpray.evaporationSource(i) + kappa*chemistry.RR(i) The problem comes from laplacian term. http://en.wikipedia.org/wiki/Schmidt_number Dt = mut/Schmidt I did not see any declaration in turbulent model. It looks like Sc always equal to 1.0, but in real application, people set that value to be 0.7 or else dependent on what turbulent model it is. Is there something wrong with my understanding? | ||||
| Tags | No tags attached. | ||||
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Most of the combustion codes in OpenFOAM are formulated based on the assumption of unity turbulent Lewis number which is commonly used in turbulent combustion. This has advantages in terms of thermodynamic consistency; it allows for a simple total enthalpy (including chemical contribution) formulation and more predictable burning rate/flame speed. However this is just one choice and if you prefer you can use a non-unity Lewis number, a non-uniform non-unity Lewis number or even a scalar-flux closure based on a Reynolds stress model all of which have advantages and disadvantages. |
| Date Modified | Username | Field | Change |
|---|---|---|---|
| 2011-08-16 05:56 | alundilong | New Issue | |
| 2011-08-16 09:20 | henry | Note Added: 0000618 | |
| 2011-08-16 09:20 | henry | Status | new => closed |
| 2011-08-16 09:20 | henry | Assigned To | => henry |
| 2011-08-16 09:20 | henry | Resolution | open => fixed |
