in many industrial equipment such as boilers and heat exchangers, the cylindrical tubes are exposed to the gas- liquid two phase flow. for any immersed body in flow field vortex shedding is created with a frequency that may be constant or variable, according to conditions such as flow rates, geometry of body, and etc. the failure will happen in the equipment, when this frequency is close to one...

Laboratory experiments have recently confirmed that the streamwise particle velocity is largely less than that of the fluid in sediment-laden flows. This velocity lag is investigated analytically in the present study based on the drag force exerting on a particle in the presence of other neighbors. The normalized drag force or the hindrance coefficient is found generally dependent on the partic...

Plants growing in rivers and lakes experience drag forces imposed by flowing water. In order to reduce the drag, plants reconfigure and streamline themselves at multiple scales. The ability of plants to reconfigure depends on their morphological and bio-mechanical properties. The plant leaves play an important role in this process which is still to be better defined and quantified. Therefore, t...

Abstract In this paper, unsteady laminar flow around a circular cylinder has been studied. Navier-stokes equations solved by Simple C algorithm exerted to specified structured and unstructured grids. Equations solved by staggered method and discretization of those done by upwind method. The mean drag coefficient, lift coefficient and strouhal number are compared from current work at three diffe...

Efficient swimming at low Reynolds numbers is a major concern of microbots. To compare the efficiencies of different swimmers we introduce the notion of "a swimming drag coefficient" which allows for the ranking of swimmers. We find the optimal swimmer within a certain class of two-dimensional swimmers using conformal mapping techniques.

Two formulas are proposed for explicitly evaluating drag coefficient and settling velocity of spherical particles, respectively, in the entire subcritical region. Comparisons with fourteen previously-developed formulas show that the present study gives the best representation of a complete set of historical data reported in the literature for Reynolds numbers up to 2×10.

Several authors have now suggested that some interstellar clouds above the plane of the Galaxy are interacting with the Reynolds’ layer, the warm ionized gas extending well above (H ∼= 910 pc) the Galactic plane (Reynolds 1993). Characterizing the interaction between these clouds and their surroundings should be useful in understanding one source of interstellar turbulence: vertical shear flows...