ANSYS FLUENT 12.0 User's Guide - 8.3.4 Density as a Profile Function of Temperature

8.3.4 Density as a Profile Function of Temperature

If you are modeling a problem that involves heat transfer, you can define the density as a function of temperature. Three types of functions are available:

piecewise-linear:

$\rho (T) = \rho_n + \frac{\rho_{n+1} - \rho_{n}}{T_{n+1} - T_{n}} (T - T_n)$ (8.3-1)
piecewise-polynomial:

$\displaystyle \mbox{for} \; T_{{\rm min},1} \leq T < T_{{\rm max},1}: \; \rho (T) = A_1 + A_2 T + A_3 T^2 + ...$ (8.3-2)

$\displaystyle \mbox{for} \; T_{{\rm min},2} \leq T < T_{{\rm max},2}: \; \rho (T) = B_1 + B_2 T + B_3 T^2 + ...$ (8.3-3)
polynomial:

$\rho (T) = A_1 + A_2 T + A_3 T^2 + ...$ (8.3-4)

For one of the these methods, select piecewise-linear, piecewise-polynomial, or polynomial in the Density drop-down list. You can enter the data pairs ( $T_n , \rho_n$ ), ranges and coefficients, or coefficients that describe these functions using the Create/Edit Materials dialog box, as described in Section 8.2.

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$\displaystyle \mbox{for} \; T_{{\rm min},1} \leq T < T_{{\rm max},1}: \; \rho (T) = A_1 + A_2 T + A_3 T^2 + ...$			(8.3-2)
$\displaystyle \mbox{for} \; T_{{\rm min},2} \leq T < T_{{\rm max},2}: \; \rho (T) = B_1 + B_2 T + B_3 T^2 + ...$			(8.3-3)