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Tiberious

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## Homework Statement

(a) The Grashof number and the Reynolds number appear in most correlations of experimental data for convective heat transfer. Explain, in a maximum of 150 words, the mechanisms of natural and forced convection with particular reference to the above non- dimensional groups.

**SOLUTION**

Heat transfer when referring to the forced or free movement of fluids is called convection. In natural (Free) convection, the fluid moves by difference in fluid densities owing due to changes in temperature gradient’s and can be represented by the Grashof number.

The Grashof number (Gr), approximates the ratio of buoyancy to viscous forces acting on a fluid.

In forced convection, the fluid is moved via influence of a pump; fan or external force. This is represented by the Reynolds number.

The Reynolds number (Re), is a nondimensional number that provides an indication whether fluid flow will be laminar or turbulent. The below image, Figure 1a, taken from Gary Settles PhD, ‘Laminar-turbulent transition’,

*unknown*, 2ndApril 2018. Shows the change of flow from a candle from laminar too turbulent flow.

Is this a reasonable answer ?