We investigate the unsaturated horseshoe drag exerted on a low-mass planet by an isothermal gaseous disk. In the globally isothermal case, we use a formalism, based on the use of a Bernoulli invariant, that takes into account pressure effects, and that extends the torque estimate to a region wider than the horseshoe region. We find a result that is strictly identical to the standard horseshoe d...

Different from conventional streamwise-aligned riblets, converging and diverging (C–D) riblets are arranged obliquely along the main-flow direction, intending to induce a large-scale secondary flow that modulates or controls existing vortical structures in wall turbulence. In this study, we perform direct numerical simulations of turbulent over C–D at low Reynolds number investigate impacts on ...

The vertical redistribution of the geostrophic momentum by the residual effects of pressure perturbations (called the layer-thickness form drag) is investigated using thickness-weighted temporal-averaged mean primitive equations for a continuously stratified fluid in an adiabatic formulation. A four-box energy diagram, in which the mean and eddy kinetic energies are defined by the thickness-wei...

A specific feature of three-dimensional bluff body wakes, flow bistability, is a subject of particular recent interest. This feature consists of a random flipping of the wake between two asymmetric configurations and is believed to contribute to the pressure drag of many bluff bodies. In this study we apply the modelling approach recently suggested for axisymmetric bodies by Rigas et al. (J. Fl...

A satellite, in its orbit, is affected by perturbing forces, such as atmospheric drag, solar radiation pressure, Earth oblateness, and gravity of the celestial masses (other than the Earth). In this paper, the effects of these forces on the trajectories of different types of LEO satellites and a sample satellite (Z-SAT) are discussed. A few analyses are done on these orbits and the relevant res...

This project analyzes 2-D, inviscid, steady supersonic flow over different airfoil designs at Mach 2.2 while at 60,000ft. The airfoils tested have sharp leading and trailing edges. The shapes range from diamond to convex to a combination of the two. A hybridization of Computational Fluid Dynamics (CFD) and Computational Acoustic simulations are used to obtain values for the lift coefficient, dr...

A series of experiments is presented which demonstrate significant drag reduction for the laminar flow of water through microchannels using hydrophobic surfaces with well-defined micron-sized surface roughness. These ultrahydrophobic surfaces are fabricated from silicon wafers using photolithography and are designed to incorporate precise patterns of microposts and microridges which are made hy...

A momentum balance approach is used to extract the drag from flowfield computations for wings and wing/bodies in subsonic/transonic flight. The drag is decomposed into vorticity, entropy, and enthalpy components which can be related to the established engineering concepts of induced drag, wave and profile drag, and engine power and efficiency. This decomposition of the drag is useful in formula...

in this paper, fluid flow between two parallel flat plates that are partially filled with two-dimension porous media is investigated numerically using single relaxation time (srt) lattice boltzmann method (lbm) at pore scale. the considered obstacles are random, circular, rigid and granular with uniform diameters. single component and single-phase viscous newtonian fluid are considered as worki...