FLOW AND HEAT TRANSFER IN AN ALMOST CIRCULAR MICROTUBE WITH ROUGH WALLS

Steady laminar flow of an incompressible fluid through a tube of almost circular cross-section is examined analytically, first for the case of a tube whose wall is wavy in the azimuthal direction, and then for one wavy in the axial direction. For the first case, a complete solution of the flow and forced convection heat transfer (for constant flux at the boundary) is possible for a wall of arbitrary cross-section. It is shown that, for a fixed axial pressure gradient, any departure from circularity leads to a reduction in volume flux and a reduction in heat transfer. For the second case no simple analytic solution is possible, but estimates of the increase in resistance due to a departure from circularity have been made.