Shear Drag Coefficient Research Articles

Computational and Physical Examination About the Aspects of Fluid Flow Between Two Coaxially Rotated Disks by Capitalizing Non-fourier Heat Flux Theory: Finite Difference Approach

This pagination is executed to exemplify flow features exhibited by viscous fluid between two coaxially rotated disks. Thermal analysis is performed by using Cattaneo-Christov heat flux theory. Porosity aspects are also taken in to account. Mathematically structured non-linear PDEs are transmuted into non-linear ODEs by employing Karman transformations. Afterwards, solution is heeded by applying implicit finite difference scheme renowned as Keller box method. Interpretation of flow controlling parameters on axial, tangential and radial components of velocity, thermal distribution is exhibited. Assurance of computed data is done by managing comparison for skin friction coefficients at walls of disks. From the attained outcomes it is addressed that the magnitude of axial and radial velocities diminishes at lower disk contrary to upper disk for intensifying magnitude of Reynold number. Increment in tangential component of velocity is also demonstrated for uplifts values of Reynold number. It is also concluded that thermal field decrements for increasing of Pr and thermal relaxation parameter. It is worthy to mention that shear drag coefficient at wall of lower disk decreases conversely to the wall shear coefficient magnitude at wall of upper disk.

Heat transfer analysis of viscous fluid flow between two coaxially rotated disks embedded in permeable media by capitalizing non-Fourier heat flux model

Current analysis illustrates the systematic survey about the flow features imparted by viscous fluid between two coaxially rotated disks embedded in a permeable medium. Energy equation has been built by encompassing Cattaneo–Christov heat flux law.Prevailing non-linear PDEs are converted into non-linear ODEs by utilizing Von Karman transformations. Afterwards, the attained differential system is solved by capitalizing implicit finite difference scheme. Interpretation regarding the impact of dimensionless involved parameters on axial, tangential and radial components of velocity, thermal distribution is exhibited. Comparison for skin friction coefficients on walls of disks is also manifested. An excellent agreement with previous work is established which assures the reliance of present work. After getting through intellect about the variations it is disclosed that the magnitude of axial and radial velocities diminishes at lower disk contrary to upper disk for intensifying magnitude of Reynold number. Furthermore, the shear stress rate at walls of upper and lower disks is also deliberated. Increment in tangential component of velocity is also manifested for uplifts values of Reynold number. In case of thermal distribution, it is deduced that thermal field decrements for increasing of Pr and thermal relaxation parameter. It is worthy to mention that shear drag coefficient at wall of lower disk decreases conversely to the wall shear coefficient magnitude at wall of upper disk.

Numerical Analysis of 3‐D Flow Past a Stationary Sphere with Slip Condition at Low and Moderate Reynolds Numbers

Computations are performed to determine the steady 3‐D viscous fluid flow forces acting on the stationary spherical suspended particle at low and moderate Reynolds numbers in the range of 0.1≤Re≤200. A slip is supposed on the boundary so that the slip velocity becomes proportional to the shear stress. This model possesses a single parameter to account for the slip coefficient λ (Pa.s/m), which is made dimensionless and is called Trostel number (Tr=λ a/μ). Decreasing slip, increases drag in all Reynolds limits, but slip has smaller effects on drag coefficient at lower Reynolds number regimes. Increasing slip at known Reynolds number causes to delay of flow separation and inflect point creation in velocity profiles. At full slip conditions, shear drag coefficient will be zero and radial drag coefficient reaches to its maximum values. Flow around of sphere at full‐slip condition is not equal to potential flow around a sphere. Present numerical results corresponding to full slip (Tr→0) are in complete accord with certain results of flow around of inviscid bubbles, and the results corresponding to no‐slip (Tr→∞) have excellent agreement with the results predicted by the no‐slip boundary condition.

Theoretical and measured aeolian sand transport on a barrier island, Louisiana, USA

ABSTRACTOver the past 100 years, the Isles Dernieres, a low lying barrier island chain along the coast of central Louisiana, Usa, has undergone more than 1 km of northward beach face retreat with the loss of 70% of its surface area. The erosion results from a long term relative sea level rise coupled with day to day wind and wave action that ultimately favours erosion over deposition. At a site in the central Isles Dernieres, 8 days of wind and beach profile measurements during the passage of one winter cold front documented aeolian erosion and deposition patterns under both onshore and offshore winds. For offshore winds, the theoretical erosion rate, based on wind shear velocity, closely matched the measured erosion rate; for onshore winds, the theoretical rate matched the measured rate only after being corrected by a factor that accounted for beach face morphology.In late February 1989, a strong cold front moved into coastal Louisiana. That cold front stalled over the Gulf of Mexico, resulting in 4 days of strong northerly winds at a study site on the Isles Dernieres. During those 4 days, the wind moved sand from the backshore to the upper beach face. When the cold front finally moved out of the area, the wind shifted to the south and decreased in strength. The onshore wind then restored some of the upper beach face sand to the backshore while increased wave activity moved the rest into the nearshore.The theoretical estimate of 1·28 m3 m−1 for the rate of sand transport by the northerly wind compares well with the measured backshore erosion rate of 1·26 m3 m−1, which was determined by comparing beach profiles from the start and end of the period of northerly winds. The theoretical estimate of 0·04 m3 m−1 for the rate of sand transport by the southerly wind, however, is notably less than the measured rate of 0·45 m3 m−1. The large discrepancy between the two rates can be explained by a difference in the shear velocity of the wind between the beach face, where the erosion occurred, and the backshore, where the wind stress was measured. Using an empirical relationship for the wind shear drag coefficient as a function of coastal environment, the theoretical estimate for the rate of sand transport by the southerly wind becomes 0·44 m3 m−1

Tests of frazil collector lines to assist ice cover formation

A preliminary investigation was made of the effect of frazil ice on arrays of lines positioned in flowing water under winter conditions. It was found that the lines would provide a stable basis for forming an ice cover on many stream reaches that would normally remain open because of high velocity and shallow depths.Tests were conducted in a refrigerated flume and in small mountain rivers. Flume depths varied from 2 – 22 cm and river depths varied from 33–50 cm. Average flow velocities had a range of 0.08–0.84 m/s in the flume and a range of 0.6–0.8 m/s in the rivers. Frazil ice would grow on a line quite rapidly achieving a diameter of 32 mm in 15 min, on a 3.2 mm dia, line in the flume. In the river, overnight accumulations reached 20 cm in depth. A few drag force measurements were made which yielded an average shear drag coefficient of 0.16.The results suggest methods of increasing our control over ice.