The convection and conduction heat flows are parallel to each other and to the surface normal of the boundary surface, and are all perpendicular to the mean fluid flow in the simple case. The amount of heat transfer is expressed by the local Nusselt number Nux, which is defined as the ratio of convective to conductive radial heat transfer. Here is how the Nusselt number for smooth tubes and fully developed flow calculation can be explained with given input values -> 10.36495 0.625(16000.7)0.4. A larger Nusselt number corresponds to more active convection, with turbulent flow typically in the 100–1000 range. To use this online calculator for Nusselt number for smooth tubes and fully developed flow, enter Reynolds Number (Re D) & Prandtl Number (Pr) and hit the calculate button. A similar non-dimensional parameter is Biot Number, with the difference that the thermal conductivity is of the solid body and not the fluid.Ī Nusselt number close to one, namely convection and conduction of similar magnitude, is characteristic of " slug flow" or laminar flow. The conductive component is measured under the same conditions as the heat convection but with a (hypothetically) stagnant (or motionless) fluid. Named after Wilhelm Nusselt, it is a dimensionless number. In this context, convection includes both advection and diffusion. In heat transfer at a boundary (surface) within a fluid, the Nusselt number ( Nu) is the ratio of convective to conductive heat transfer across ( normal to) the boundary.
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