Convective heat transfer in periodic wavy passages

An experimental study of flow and heat transfer in sinusoidal wavy passages

Enhanced heat transfer due to curvature-induced lateral vortices in laminar flows in sinusoidal corrugated-plate channels

A key need for dynamic single-cell measurements is the ability to gently position cells for repeated measurements without perturbing their behavior. We describe a new method that uses a gentle secondary flow to trap and suspend single cells, including motile cells, at predictable locations in 3-D. Trapped cells can be more dense or less dense than the surrounding medium. The cells are suspended without surface contact in one of four steady streaming eddies created by audible-frequency fluid oscillation (< or =1000 Hz) in a microchannel containing a single fixed cylinder (radius = 125 microm). Comparison of measured trap locations to computations of the eddy flow show that each trap is located near the eddy center, and the location is controlled via the oscillation frequency. We use the motile phytoplankton cell (Prorocentrum micans) to experimentally measure the trapping force, which is controlled via the oscillation amplitude. Trapping forces up to 30 pN are generated while exerting moderate shear stresses (shear stresses < or = 1.5 N/m2) on the trapped cell. The magnitude of this trapping force is comparable to that of optical tweezers or dielectrophoretic traps, without requiring an external field outside the physiological range for cells (the shear stresses are comparable to those found in arterial blood flow). The unique combination of predictable 3-D positioning, insensitivity to cell and medium properties, strong adjustable trapping forces, and a gentle fluid environment makes hydrodynamic tweezers a promising new option for noncontact trapping of single cells in suspension.

Hydrodynamic tweezers: 1. Noncontact trapping of single cells using steady streaming microeddies.

Oscillatory flow reactors (OFRs) for continuous manufacturing and crystallization

Flow characteristics in a channel with a symmetric wavy wall were investigated by calculations and experiments. The channel used has a geometry similar to that of the Oxford membrane blood oxygenator. The flow regime covered ranged from laminar to turbulent flow. The variation of pressure drop and wall shear stress with the Reynolds number was elucidated by the behavior of the circulated vortex formed at the diverging cross section of the channel.

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Flow characteristics in a channel with symmetric wavy wall for steady flow.

Natural convection heat transfer in enclosures with multiple vertical partitions

The occurrence and structure of longitudinal vortices are examined by a flow visualization technique for various sinusoidal wavy channels Longitudinal vortices are confirmed to appear in a channel with a narrow spacing in the range of geometrical parameters considered here The geometrical conditions for the onset of such vortices are shown by a diagram The longitudinal vortex is a kind of Taylor–Goertler vortex observed in a curved rectangular-section channel However, the wavy channel is different from the curved rectangular-section channel in the processes of vortex development and destruction It is found that an unstable mode, in which the vortices formed at the upper and lower walls of the channel have some interaction, leads to vortex destruction and significantly promotes the transition to turbulence

Occurrence and Structure of Taylor–Goertler Vortices Induced in Two-Dimensional Wavy Channels for Steady Flow

Mass transfer characteristics in a channel with symmetric wavy wall were investigated by the Leveque theory and the electrochemical method. The channel used has a geometry similar to that of the Oxford membrane blood oxygenator. The flow regime covered ranged from laminar to turbulent flow. The local Sherwood number distributions indicate that the reversed-flow region significantly differs from the forward-flow region in mass transfer characteristics. For laminar flow, mass transfer enhancement of the wavy channel is scarcely expected as compared with the corresponding straight channel, but is found to be remarkable for turbulent flow.

Mass transfer characteristics in a channel with symmetric wavy wall for steady flow.

Resultats experimentaux de perte de charge, de diagramme d'ecoulement et de transfert de matiere

Yuji Kawamura

Papers

Flow characteristics in a channel with symmetric wavy wall for steady flow.

Natural convection heat transfer in enclosures with multiple vertical partitions

Occurrence and Structure of Taylor–Goertler Vortices Induced in Two-Dimensional Wavy Channels for Steady Flow

Mass transfer characteristics in a channel with symmetric wavy wall for steady flow.

Mass transfer enhancement in channels with a wavy wall