Lecture Objectives LES Multizone modeling Examples of LES

Lecture Objectives • LES • Multizone modeling

Examples of LES: • • https: //www. youtube. com/watch? v=y. RSoil. RCu. Es https: //www. youtube. com/watch? v=y 1 s. SRXFBN 7 k https: //www. youtube. com/watch? v=d. We 3 fnfo 9 WQ https: //www. youtube. com/watch? v=e 1 Tbk. LIDWys https: //www. youtube. com/watch? v=i. JIRrk 7 t. Kws https: //www. youtube. com/watch? v=NClf. Gdfw. WTA https: //www. youtube. com/watch? v=hz 7 Uj. N_v. Yuw

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

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: So no additional transport equation! This is Sub. Grid Scale (SGS) model Smagorinsky model (1963) eddy viscosity is model There are Many more: Algebraic Dynamic model Dynamic Global-Coefficient model Localized Dynamic model

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

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