Learning Forum

[Muzzammil]

I am performing heat transfer simulation using nanoparticles using multiphase Eulerian approach. While giving boundary conditions, i came across Granular temperature (which is the kinetic energy per unit mass possessed by the particle). I am unable to calculate it. Kindly help me in this regardn

[Surya Deb]

Thank you for your answer Kkanade.nKnowing it's possible to sim both internal and external will save me a lot of time at work. Even though that might seem counter-intuitive.nHowever I have a follow-up question:nI was taught to calculate my first layer height based on the desired Y+ of the viscous model (in this case 1 + + ) where u', v' and w' are velocity fluctuations of the granular media along x,y and z directions respectively. The mean of these fluctuations are generally zero over time. Also the <> indicates ensemble averaging. nIf the fluctuations are low, you can use the default values. You will find more information on this in open literature.nRegards,nSDn

[Surya Deb]

A small correction, it would be 1/3rd and not 1/2 before the squared terms.n

[Muzzammil]

Thanks for that, but how can i determine that velocity fluctuation component, is there any other relation for granular temperaturenn

[Surya Deb]

Hello, nThere is no explicit formulation for this but you would have to use Kinetic Theory or equations similar to above to estimate the inlet/outlet granular temperatures. nIf the particulate flow is uniform, then you can expect very low deviation of the fluctuations from the average value and consequently the granular temperature will be low as well. The reverse is true if the particles are randomly moving. Generally, a Maxwellian velocity distribution can be used as an approximation.nBut most promising would be to obtain experimental or test data in regards to particle stress or particle velocity fluctuations in those locations. Generally PIV technique has been used to obtain such information in existing literature.nRegards,nSDn