Modeling > Modeling Turbulence > Using Wall Treatment Models > Formulation of Wall Laws > Asymptotic Limits

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Asymptotic Limits

The wall laws differ only in their treatment in the buffer region; the viscous-sublayer and log-layer behaviors are identical.

Viscous Sublayer

The velocity distribution is modeled as:

(146)

The temperature distribution (in the absence of viscous dissipation) is modeled as:

(147)

The effect of viscous dissipation is introduced by the non-dimensional quantity:

(148)
Logarithmic Layer

The velocity distribution is modeled as:

(149)

where:

(150)

and the default values of the coefficients are  = 0.42 and E = 9.0. The value of the roughness function in Eqn. (150) is unity for smooth walls, and for rough walls is computed according to Eqn. 165.

The temperature distribution (in the absence of viscous dissipation) is modeled as:

(151)

where the function P, which governs the velocity at which the logarithmic and viscous regions of the thermal profiles intersect, is by Jayatilleke [15]:

(152)

and is the molecular Prandtl number and is the turbulent Prandtl number.

The effect of viscous dissipation is introduced by the non-dimensional quantity:

(153)

where is a fictitious non-dimensional velocity that would occur at the intersection of the laminar and turbulent temperature profiles. It is computed from Eqn. 152 as:

(154)

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