the multiple reference frames (mrf) method is the most suitable method tosimulate impeller rotation in mixing systems. precise determination of stationaryand moving zones in mrf method leads to accurate results in mixing performance.in this research, the entire volume of mixing system was divided into two zones.the kinetic energy values were used to distinguish the zones with differentvelocitie...

Abstract—In this work, numerical simulations were carried out using a specific CFD code in order to study the performance of an innovative Scraped Surface Heat Exchanger (SSHE) with helical ribbons for Bingham fluids (threshold fluids). The resolution of threedimensional form of the conservation equations (continuity, momentum and energy equations) was carried out basing on the finite volume me...

This paper explores the effect of impeller design on the chaotic mixing in a helical ribbon mixer. Numerical simulations using the Smoothed Particle Hydrodynamics (SPH) method are used to solve for the fluid flow around the moving impellor. The mixing flow is visualised by extracting the hyperbolic Lagrangian Coherent Structures (LCS) of the flow from the Finite-Time Lyapunov Exponent (FTLE) fi...

The Arc repressor of bacteriophage P22 is a dimeric member of the ribbon-helix-helix family of transcription factors. Residues 9-14 of each wild-type Arc subunit pair to form two antiparallel beta-strands and have the alternating pattern of polar and nonpolar residues expected for a beta-ribbon with one solvent-exposed face and one face that forms part of the hydrophobic core. Simultaneously sw...

Both intact and nuclease-isolated chromatin fibers have been examined at different degrees of salt-induced compaction, using a variety of preparation techniques. The results suggest that the initial folding step in nucleosome packing involves the formation of a zig-zag ribbon as has been proposed by others (Thoma F., T. Koller, and A. Klug, 1979, J. Cell Biol., 83:403-427; Worcel A., S. Strogar...

We report the discovery of an entirely new three-dimensional (3D) swimming pattern observed in human and horse sperms. This motion is in the form of 'chiral ribbons', where the planar swing of the sperm head occurs on an osculating plane creating in some cases a helical ribbon and in some others a twisted ribbon. The latter, i.e., the twisted ribbon trajectory, also defines a minimal surface, e...

A method for the cultivation of embryo chick tissues which gave rise to numerous and unusually large crystals and particles is detailed. Forms were helical, tubular, ribbon-like, hexagonal, rhomboidal, and filamentous. Rhomboids and hexagonals often had surface areas several times the size of the broad and flat tissue-cultured cells, and helices were observed up to 300 @ in length. Transformati...

We propose a model for the self-propulsion of the marine bacterium Synechococcus utilizing a continuous looped helical track analogous to that found in Myxobacteria [1]. In our model cargo-carrying protein motors, driven by proton-motive force, move along a continuous looped helical track. The movement of the cargo creates surface distortions in the form of small amplitude traveling ridges alon...

A graphene nanoribbon with armchair edges is known to have no edge state. However, if the nanoribbon is in the quantum spin Hall state, then there must be helical edge states. By folding a graphene ribbon into a ring and threading it by a magnetic flux, we study the persistent charge and spin currents in the tight-binding limit. It is found that, for a broad ribbon, the edge spin current appr...