Search results for "Drag coefficient"
showing 4 items of 14 documents
The Dynamics of Eye Formation and Maintenance in Axisymmetric Diabatic Vortices
2009
Abstract This paper investigates the occurrence, formation, and maintenance of eyes in idealized axisymmetric balanced vortices with diabatic forcing. Two key elements of the model setup are temperature relaxation toward a specified equilibrium temperature Te and Ekman pumping from a turbulent boundary layer. Furthermore, the flow is assumed to be almost inviscid in the interior. The model does not attempt any closure for moist convection. Previous work by the authors has shown that there is a continuous transition from monsoonlike vortices to hurricane-like vortices. This transition is governed by the ratio ℱ = αT /cD, where αT is the thermal relaxation rate and cD the surface drag coeffic…
CFD Simulation of Particle Distribution in a Multiple-impeller High-Aspect-Ratio Stirred Vessel
2000
Publisher Summary This chapter describes fully predictive simulations of solid–liquid suspensions in a high-aspect-ratio, multiple-impeller stirred tank. These are performed by using the Inner Outer impeller modeling technique coupled with the Multi Fluid Model (MFM) for the treatment of the dispersed phase. The strongly simplified Settling Velocity Model (SVM) is also tested. The effects of free-stream turbulence on the drag coefficient CD and particle settling velocity are accounted for by means of a recently proposed correlation. Comparison of simulation results with experimental particle concentration profiles shows that the MFM approach leads to fair agreement with experimental data. R…
The unusual hydrodynamical behaviour of freshwater oncolites
1997
Algal concretions are frequent in calcareous environments, occuring as individual particles (oncolites) that are easily transported during floods. Several parameters have been measured and calculated for a population of 127 particles from French streams. These oncolites have a high porosity (mean 42.7%) and a low density (mean 1.65), in respect to quartz and calcite. Oncolites have a settling velocity 1.5 times lower than that of quartz grains with the same nominal diameter. The computation of multiple correlations results in a classification in terms of decreasing efficiency: shape coefficients (Corey, ψ, and SI of Sneed and Folk), nominal diameter, density, edge sharpness and roughness. A…
Validity of a novel device for indoor analysis of cyclists' drag area
2021
Cyclists need to measure aerodynamic resistance accurately and reliably, as well as economically. Devices such as Notio Aerostick, an equipment device that includes one pitot tube, have appeared for this purpose. The aim of this study is, therefore, to test the reliability and degree of agreement in the evaluation of the CdA (coefficient of aerodynamic drag), assessed by means of the Notio Aerostick compared to the Virtual Elevation (VE) and Martin mathematical models.Seventeen professional cyclists rode in a 250-metre-long velodrome covered with a concrete surface with their own time trial bikes. Each cyclist completed three rides of 15 laps at constant speed for the evaluation of the CdA,…