Heat transfer—A review of 2003 literature

Developing forced convection in converging–diverging microchannels

Viscous flow in variable cross-section microchannels of arbitrary shapes

Microscale steady streaming eddies created using low-intensity fluid oscillations offer appealing options for controlling fluids in microfluidic systems. We describe the three-dimensional (3D) steady streaming flow formed in a small channel containing single fixed cylinders when the channel fluid is oscillated at low intensity. Experiments include three cylinder sizes (length 1.5mm; radii a=125, 250, and 500μm) within identical channels (height 2h=1.5mm; width 4mm) over a range of oscillation frequencies (40⩽ω⩽1000Hz). The size of key flow features is measured from steady particle pathline images recorded within three flow symmetry planes. The resulting 3D streaming exhibits two distinct recirculating flows that are governed by the Stokes layer thickness δAC and geometric length scales. Four symmetric recirculating eddies are created adjacent to the cylinder far from channel walls, and their size is governed by δAC∕a as described by steady streaming theory for a 2D geometry. The cylinder/wall boundary lay...

Microscopic steady streaming eddies created around short cylinders in a channel: Flow visualization and Stokes layer scaling

Fully developed flow and heat transfer characteristics in a wavy passage: Effect of amplitude of waviness and Reynolds number

Flow and mass transfer characteristics in an axisymmetric sinusoidal wavy-walled tube are investigated experimentally in the Reynolds number range from 50 to 1000 The flow patterns are visualized by the aluminum dust method The measurements of the wall shear stress and the mass transfer rate for high Schmidt number are performed by the electrochemical method The attention is focused on their characteristics, including the transitional flow It was observed that steady flow changes into unsteady flow when the Reynolds number exceeds about 160 The wall shear stress in the minimum circular cross section of the tube and the mass transfer rate for one wavelength are shown to depend upon the Reynolds number In the laminar flow regime they increase with the slope of 1 and 1/3, respectively, whereas in the turbulent flow regime they increase with the slope of 3/2 and 3/5, respectively In the transitional flow regime both of them increase significantly with further larger slope It is found that the laminar-like motion and turbulent-like motion occur alternatively, with different time intervals, indicating intermittent flow behavior This is quite different from the flow instability of the wavy-walled channel in which Tollmien-Schlichting waves keeping a time-periodic flow appear

Fluid flow and mass transfer characteristics in a sinusoidal wavy-walled tube at moderate Reynolds numbers for steady flow

Flow and mass transfer characteristics in an axisymmetric sinusoidal wavy-walled tube are investigated experimentally in the Reynolds number range from 50 to 1000. The flow patterns are visualized by the aluminum dust method. The measurements of the wall shear stress and the mass transfer rate for high Schmidt number are performed by the electrochemical method. The attention is focused on their characteristics, including the transitional flow. It was observed that steady flow changes into unsteady flow when the Reynolds number exceeds about 160. The wall shear stress in the minimum circular cross section of the tube and the mass transfer rate for one wavelength are shown to depend upon the Reynolds number. In the laminar flow regime they increase with the slope of 1 and 1/3, respectively, whereas in the turbulent flow regime they increase with the slope of 3/2 and 3/5, respectively. In the transitional flow regime both of them increase significantly with further larger slope. It is found that the laminar-like motion and turbulent-like motion occur alternatively, with different time intervals, indicating intermittent flow behavior. This is quite different from the flow instability of the wavy-walled channel in which Tollmien-Schlichting waves keeping a time-periodic flow appear.

Y. N. Bian

Papers

Fluid flow and mass transfer characteristics in a sinusoidal wavy-walled tube at moderate Reynolds numbers for steady flow

Fluid flow and mass transfer characteristics in a sinusoidal wavy-walled tube at moderate Reynolds numbers for steady flow