The classical problem of suppressing vortex shedding in the wake of a circular cylinder by using body rotation is revisited in an adjoint-based optimal control framework. The cylinder’s unsteady and fully unconstrained rotation rate is optimized at Reynolds numbers between 75 and 200 and over horizons that are longer than in previous studies, where they are typically of the order of a vortex sh...

the gravity method is one of the first geophysical techniques used in oil and gas exploration. an algorithm is developed for a fast quantitative interpretation of gravity data generated by geometrically simple but also the estimated depths and other model parameters of a buried structure. following abdelrahman et al (1989). the general gravity anomaly expression produced by a sphere, an infinit...

We study the motion of a cylindrical particle translating slowly in a long tube as a function of the particle's dimensions and placement both in the presence and the absence of external pressure gradients. The cylinder acts as a "leaky" piston, generating both fluid recirculation and through flow. When the particle is long, analytic expressions are obtained for both the velocity field and the f...

the effective factors of forward speed, cylinder rotation, and clearance between a combine’s cylinder and concave on wheat kernel breakage and seed germination were studied in karaj area using a 955 model john dear combine. this study was conducted on three levels of adjustment for each of the variables, 1.2, 1.8 and 2.5 km/hr for forward speed, 800, 900, 1000 rpm for cylinder rotation as well ...

The development of the boundary layer along a long thin cylinder aligned with the flow is considered. Numerical solutions are presented and compared with previous asymptotic results. Very near the leading edge the flow is given by the Blasius solution for a flat plate. However, there is soon a significant deviation from Blasius flow, with a thinner boundary layer and higher wall shear stress. L...

In this study, some parameters such as quenching and boiling curves of a stainless steel cylindrical rod 80 mm long and having a diameter of 15 mm were experimentally obtained in saturate pure water and two nanofluids (SiO2 and TiO2) with 0.01 wt%. The cylinder was vertically lowered into the pool of saturated water and its temporal center temperature was measured by a the...

We presume that plane strain state of deformation prevails when the interior of a long gun barrell or a cylindrical pressure vessel is dynamically loaded. The viscoplastic material of the body-is taken to exhibit strain-rate hardening and thermal softening. Two thin ellipsoidal voids located symmetrically on the horizontal axis and near the center of the cylinder wall act as nuclei for the init...

We report upon an experimental study of internal gravity waves generated by the large-amplitude vertical oscillations of a circular cylinder in uniformly stratified fluid. Quantitative measurements are performed using a modified synthetic schlieren technique for strongly stratified solutions of NaCl or NaI. The oscillatory forcing leads to the development of turbulence in the region bounding th...

Axisymmetrical stresses in an infinitely long hollow isotropic circular cylinder (plane strain) quickly approach their asymptotic values as the external radius increases. This is not the case if the cylinder is even slightly anisotropic -asymptotic solutions (for an infinitely large external radius) do not exist. We find the mechanical meaning of this disparity by using formulas for radial and ...