We report a novel and spectacular instability of a fluid surface in a rotating system. In a flow driven by rotating the bottom plate of a partially filled, stationary cylindrical container, the shape of the free surface can spontaneously break the axial symmetry and assume the form of a polygon rotating rigidly with a speed different from that of the plate. With water, we have observed polygons...

Based on the three-dimensional elliptic governing equations and the throttle model, an unsteady numerical simulation of rotating stall is undertaken in the case of G4-73 type centrifugal fan and the correctness of simulation results is verified by experiments. In this study a new rotating stall inception criterion is put forward, that the inlet flow or outlet back pressure fluctuations graduall...

The Shear-slip Mesh Update Method (SSMUM) is being used in flow simulations involving large but regular displacements of one or more boundaries of the computational domain. We follow up the earlier discussion of the method with notes on practical implementation aspects. In order to establish a benchmark problem for this class of flow problems, we define and report results from a two-dimensional...

Expanding upon recent applications of interfacing electricity with centrifugal microfluidic platforms, we introduce electrochemical velocimetry to monitor flow in real-time on rotating fluidic devices. Monitoring flow by electrochemical techniques requires a simple, compact setup of miniaturized electrodes that are embedded within a microfluidic channel and are connected to a peripherally-locat...

3 The Rotating Calipers Algorithm 3 3.1 Computing the Initial Rectangle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 3.2 Updating the Rectangle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 3.2.1 Distinct Supporting Vertices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 3.2.2 Duplicate Supporting Vertices . . . . . ....

It is well known that flow instabilities called rotating stall and surge may occur in non-cavitating turbomachines at flow rates smaller than design. Rotating stall is a local instability at the turbomachinery which is basically not dependent on the hydraulic system in which the turbomachine is installed. The stalled region rotates faster than impeller. Surge is a system instability in a hydrau...

objective and aims intrauterine devices (iuds) are placed in the uterine cavity with the objective of providing long-term contraception, mainly by preventing fertilization. in this research has been tried to show that method of iud insertion is effective to decrease complications’ incidence . rotating withdrawal technique is presenting, has been using for this purpose. design and setting this h...

We derive the formalism to obtain spatial distributions of collisional correlation times for macroscopic particles undergoing granular flow from pulsed gradient spin echo nuclear magnetic resonance diffusion data. This is demonstrated with an example of axial motion in the shear flow regime of a 3D granular flow in a horizontal rotating cylinder at one rotation rate.

In this paper, we establish some quantity relationships between the dynamics of circular cylinder wakes and the rotation speed of the cylinder. It has been shown analytically that rotating the cylinder can regularize the flow behavior, and delay the transition from steady flow to turbulent flow. The work needed to overcome the drag exerted on the cylinder is provided.

Pre-sedimentation basins are among the most important elements of the conventional water treatment process. In pre-sedimentation basins, due to different velocity gradients, secondary and rotational flows are formed that will create short paths and increase dead and still flow zones as well as changes in the flow mixing. This will prevent laminar flow conditions for sedimentation and will reduc...