Two-dimensional adiabatic forced convection at low péclet number

1972 ◽  
Vol 25 (1) ◽  
pp. 337-348 ◽  
Author(s):  
A. S. Jones
Keyword(s):  
Forced Convection ◽  
Peclet Number ◽  
Two Dimensional ◽  
Péclet Number

Numerical Analysis of Heat Transfer Enhancement in a Micro-Channel Due to Mechanical Stirrers

2020 ◽  
Vol 13 (1) ◽  
Author(s):  
M. Sreejith ◽  
S. Chetan ◽  
S. N. Khaderi
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Transfer Enhancement ◽  
Peclet Number ◽  
Periodic Case ◽  
Two Dimensional ◽  
Transfer Enhancement ◽  
Fluidic Channel ◽  
Enhancement Of Heat Transfer ◽  
Péclet Number

Abstract Using two-dimensional numerical simulations of the momentum, mass, and energy conservation equations, we investigate the enhancement of heat transfer in a rectangular micro-fluidic channel. The fluid inside the channel is assumed to be stationary initially and actuated by the motion imparted by mechanical stirrers, which are attached to the bottom of the channel. Based on the direction of the oscillation of the stirrers, the boundary conditions can be classified as either no-slip (when the oscillation is perpendicular to the length of the channel) or periodic (when the oscillation is along the length of the channel). The heat transfer enhancement due to the motion of the stirrers (with respect to the stationary stirrer situation) is analyzed in terms of the Reynolds number (ranging from 0.7 to 1000) and the Peclet number (ranging from 10 to 100). We find that the heat transfer first increases and then decreases with an increase in the Reynolds number for any given Peclet number. The heat transferred is maximum at a Reynolds number of 20 for the no-slip case and at a Reynolds number of 40 for the periodic case. For a given Peclet and Reynolds number, the heat flux for the periodic case is always larger than the no-slip case. We explain the reason for these trends using time-averaged flow velocity profiles induced by the oscillation of the mechanical stirrers.

Effect of Peclet Number in Thermo-Mechanical Cracking Due to High-Speed Friction Load

1988 ◽  
Vol 110 (2) ◽  
pp. 217-221 ◽  
Author(s):  
F. D. Ju ◽  
J. C. Liu
Keyword(s):  
Tensile Stress ◽  
Peclet Number ◽  
High Speed ◽  
Property Values ◽  
Critical Depth ◽  
Two Dimensional ◽  
Péclet Number ◽  
Parametric Effects ◽  
The Relationship ◽  
Thermal Tensile Stress

The present paper discussed the critical depth, i.e., the depth at which the thermal tensile stress reaches a maximum, caused by the frictional excitation of a fast moving asperity. In the study, the critical depth was computed directly by maximizing the thermal tensile stress with respect to positions under the asperity inside the material. The relationship between critical depth and Peclet number for all materials in the two-dimensional formulation may be simplified to satisfy the exponential form R(ηcr)2.275=20.4368. Stellite III was chosen as the indicator material. Other parametric effects including mechanical properties and thermal properties were tested with materials having diverse property values. These tests confirmed that for the two-dimensional formulation, the Peclet number is the only one which dominates the critical depth.

scholarly journals Laminar forced convection at low Péclet number

1972 ◽  
Vol 6 (1) ◽  
pp. 83-94 ◽  
Author(s):  
A.S. Jones
Keyword(s):  
Forced Convection ◽  
Peclet Number ◽  
Asymptotic Form ◽  
Circular Tube ◽  
Physical Parameters ◽  
Heat Sources ◽  
Temperature Changes ◽  
Péclet Number ◽  
Nusselt Numbers ◽  
Laminar Forced Convection

This work is concerned with the forced convection of heat in a circular tube. The fluid flow is assumed to be laminar Poiseuille flow, and the physical parameters; viscosity, density, conductivity; are assumed to be independent of temperature changes. Viscous dissipation terms are also ignored, and there are no heat sources in the fluid. The problem is treated for the case of a step change in the wall temperature, and the eigenvalues have been obtained as an expansion in powers of the Péclet number for the smaller values, and in an asymptotic form for the larger values. The temperature distribution in the fluid in the neighbourhood of the temperature jump has been calculated for two values of the Péclet number, as have the Nusselt numbers.

The Effects of Forced Convection on the Power Dissipation of Constant-Temperature Thermal Conductivity Sensors

1997 ◽  
Vol 119 (1) ◽  
pp. 30-37 ◽  
Author(s):  
Y. Huang ◽  
H. H. Bau
Keyword(s):  
Thermal Conductivity ◽  
Forced Convection ◽  
Constant Temperature ◽  
Power Dissipation ◽  
Peclet Number ◽  
Asymptotic Theory ◽  
Time Dependent ◽  
Péclet Number ◽  
Theoretical Predictions ◽  
On Line

The effect of forced convection on the power dissipation of cylindrical and planar, constant temperature, thermal conductivity detectors (TCDs) is investigated theoretically. Such detectors can be used either for on-line continuous sensing of fluid thermal conductivity or for determining the sample concentrations in gas chromatography. A low Peclet number, asymptotic theory is constructed to correlate the TCD’s power dissipation with the Peclet number and to explain experimental observations. Subsequently, the effect of convection on the TCD’s power dissipation is calculated numerically for both time-independent and time-dependent flows. The theoretical predictions are compared with experimental observations.

Laminate Mixing in Micro-Scale Fractal-Like Merging Channel Networks

2003 ◽  
Author(s):  
Kent E. Enfield ◽  
Jeremy J. Siekas ◽  
Deborah V. Pence
Keyword(s):  
Peclet Number ◽  
Concentration Profiles ◽  
Two Dimensional ◽  
Dimensional Model ◽  
Total Flow ◽  
Initial Flow ◽  
Flow Network ◽  
Péclet Number ◽  
Flow Length ◽  
Two Dimensional Model

A two-dimensional model was developed to predict concentration profiles resulting from passive, or diffusive, mixing of laminated layers formed in a fractal-like merging flow network. Both uniform and parabolic velocity profiles were considered in the model. Concentration profiles were experimentally acquired near the top surface of the flow network using laser induced fluorescence. The degree of mixing was assessed from concentration profiles at the end of each channel. Although the degree of mixing from the two-dimensional model well predicts the trend of the experimental degree of mixing, the numerical model under predicts the experimental values by approximately 25 percent. This may be due in part to the presence of top and bottom walls in the experimental device. These walls tend to slow the flow in this region, thereby increasing the residence time and improving the mixing. These top and bottom walls are neglected in the two-dimensional model. For the existing flow network, the degree of mixing is provided as a function of Peclet number. The degree of mixing is further investigated by varying the number of branching levels, the width of the initial flow channels, and the total flow length for a fixed Peclet number. A nondimensional parameter is established that serves as a design tool for predicting an optimum number of branching levels for fixed values of the total flow length, initial branch width and channel depth.

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