Drag coefficient

About: Drag coefficient is a research topic. Over the lifetime, 14471 publications have been published within this topic receiving 303196 citations. The topic is also known as: drag factor.

A new parameterization of surface drag in the marginal sea ice zone

Abstract: A parameterization of subgridscale surface fluxes over the marginal sea ice zone which has beenused earlier in several studies is modified and applied to a nonhydrostatic mesoscale model.The new scheme accounts for the form drag of ice floes and is combined with a so-called fluxaveraging method for the determination of surface fluxes over inhomogeneous terrain. Individualfluxes over ice and water are calculated as a function of the blending height. It is shown bycomparison with observations that the drag coefficients calculated with the new parameterizationagree well with data. The original scheme strongly overestimates the form drag effect.An improvement is mainly obtained by an inclusion of stratification and by use of a moreadequate coefficient of resistance for individual ice floes. The mesoscale model is applied to officeflows over the polar marginal sea ice zone. The model results show that under certainmeteorological conditions the form drag can have a strong influence on the near-surface windvelocity and on the turbulent fluxes of momentum. Four case studies are carried out. Themaximum influence of form drag occurs in the case with strong unstable stratification and withwind oblique to the ice edge. Under these conditions the wind stress on sea ice is modified byat least 100% for ice concentrations less than 50% if form drag is taken into account. DOI: 10.1034/j.1600-0870.2002.00243.x

Theory of wing-body drag at supersonic speeds

Abstract: The relation of Whitcomb's "area rule" to the linear formulas for wave drag at lightly supersonic speeds is discussed. By adopting an approximate relation between the source strength and the geometry of a wing-body combination, the wave-drag theory is expressed in terms involving the areas intercepted by oblique planes or Mach planes. The resulting formulas are checked by comparison with the drag measurements obtained in wind-tunnel experiments and in experiments with falling models in free air. Finally, a theory for determining wing-body shapes of minimum drag at supersonic Mach numbers is discussed and some preliminary experiments are reported.

An optimum suppression of fluid forces by controlling a shear layer separated from a square prism

Abstract: This paper deals with the suppression of the fluid forces by controlling a shear layer on one side separated from a square prism. The control of the separated shear layer was established by setting up a small circular cylinder (the control cylinder) in it on one side. Experimental data were collected to examine the effects on the fluid forces and vortex shedding frequency due to variation of the position and diameter of the control cylinder. The results show that (i) the maximum reduction of the time-mean drag and fluctuating lift and drag occurred when the control cylinder was located near what would ordinarily be considered the outer boundary of the shear layer; (ii) the control of the separated shear layer by means of a small cylinder appeared to be effective in suppressing the fluctuating lift and drag rather than the time-mean drag; (iii) in the case of the control cylinder of 6 mm in diameter, the time-mean drag was reduced to about 30 percent, and the fluctuating lift and drag were reduced to approximately 95 and 75 percent, respectively; (iv) the fluid forces and the frequency of vortex shedding of the square prism were mainly dependent on the characteristics of a very thin region near the outer boundary of the shear layer.