1. Lecture Objectives
LES
Multizone modeling

2. Examples of LES: https://www.youtube.com/watch?v=yRSoilRCuEs

3. LES vs RANS RANS: LES: Low pass filter – resolve large scale eddies
Model effect of small scale eddies
Cut-off scale ∆ (space grid), cut of time scale ∆

4. LES Similar to RANS we are using effective viscosity for LES:
Gradient of velocity tensor:
is the rate-of-strain tensor for the resolved scale
Finally:
This is SubGrid Scale (SGS) model
Smagorinsky model (1963)
eddy viscosity is model
So no additional
transport equation!
There are Many more:
Algebraic Dynamic model
Dynamic Global-Coefficient model
Localized Dynamic model

5. LES Time Step Depends on the length scale and velocity
Courant–Friedrichs–Lewy (CFL) number
condition for convergence while solving hyperbolic differential equations

6. Multizone modeling CONTAM http://www.bfrl.nist.gov/IAQanalysis/
NO momentum equation
Just pressure, temperature, and continuity
Depends heavily on boundary condition and orifice coefficients that define flow between zones
Good for buoyancy driven flow