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Natural Convection (Buoyancy)
A natural convection (buoyancy) capability is available for multiphysics applications that couple steady fluid flow analysis with steady-state heat transfer analysis. Natural (or free) convection is flow induced by density gradients caused by temperature differences. There is a close connection between fluid motion and how the heat is transferred within the moving fluid. For example, when heating a pot of water on a stove, the warm, and thus lighter, fluid near the bottom rises toward the upper surface. This induces the flow of cooler, denser, fluid toward the bottom, where it is then heated and renews the cycle of motion. In contrast, when flow is induced by an external force, such as air blown over a surface by a fan, it is termed forced convection. Both natural and forced convection can occur simultaneously (mixed) in the same application. Engineers can perform a coupled fluid flow and thermal analysis and then examine the velocity and temperature results for a wide range of applications including electronics cooling and emission studies. The buoyancy force can be defined by specifying the reference temperature, acceleration due to body force,
gravity and the buoyancy load curve.
Models consist of at least one part that is considered in both the fluid and thermal analyses and any number of
additional solid parts that undergo purely heat transfer phenomena.
Thus, it is possible to simulate flows surrounded by complex, multiple-part assemblies.
An iterative process is automatically performed by the software between a steady fluid flow analysis and
a steady-state heat transfer analysis in order to converge on an accurate multiphysics solution. TYPICAL APPLICATIONS
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