Theory

The wall is not meshed: the shell is a planar layer of thickness $t$ and conductivity $k$ given to the solver's externalWallHeatFluxTemperature condition. The thickness enters twice: in the conduction resistance, and in the outer diameter of the cylinder correlations for still air and moving air (Outer environment), equation (2), where the gas-side characteristic diameter is $4V/A$ of the fluid volume and the outer walls.

Equations

R = \frac{t}{k} + \frac{t_{ins}}{k_{ins}}

(1)

D_{out} = \frac{4V}{A_{walls}} + 2\,(t + t_{ins})

(2)

where	meaning	unit
$R$	Conduction resistance of the layer stack per unit area	m² K/W
$t, k$	Shell thickness (this setting) and conductivity	m, W/(m K)
$t_{ins}, k_{ins}$	Insulation thickness and conductivity	m, W/(m K)
$D_{out}$	Outer characteristic diameter of the correlations	m
$V$	Fluid volume of the model	m³
$A_{walls}$	Total area of the outer wall patches	m²

Default and rule

Default: 1.5 mm
Rule: 1.5 mm.
Source: The planar-layer wall model is described in Thermal condition of a wall; adding the layer stack to the outer diameter is the program's own simplification.

Valid range > 0

Values

Positive. Typical muffler shells are 0.8-2 mm.

Theory

Equations

Default and rule

Valid range > 0

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