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The UMIST-N Near-Wall Treatment Applied to Periodic Channel Flow

The UMIST-N Near-Wall Treatment Applied to Periodic Channel Flow

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Chapter 2<br />

Turbulence Models<br />

<strong>The</strong> Reynolds Averaged Navier S<strong>to</strong>kes equations are obtained for continuity,<br />

conservation of momentum, and generic transport. <strong>The</strong> assumptions of the<br />

EVM are employed where appropriate. <strong>The</strong>n, specific transport equations<br />

are introduced for the turbulence parameters tracked by the k-ε and k-ω<br />

models. <strong>The</strong> logarithmic law of the wall is introduced.<br />

2.1 Reynolds Averaging<br />

Consider a flow field containing an incompressible fluid with constant proper-<br />

ties: density (ρ), dynamic viscosity (µ), and kinematic viscosity (ν = µ<br />

). In ρ<br />

Cartesian coordinates, the flow field extends in three orthogonal directions,<br />

x, y, and z. <strong>The</strong> flow field may vary in time, t. A pressure field, P (x, y, z, t)<br />

and a velocity field, U (x, y, z, t) = (U, V, W ) T are associated with the flow.<br />

This flow field is governed by continuity and the conservation of momentum.<br />

17

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