Papers by Keyword: Shear Flow

Abstract: Morphological evolution of a transparent model succinonitrile (SCN) material during solidification was investigated in an apparatus resembling a shearing-disc viscometer. The in situ microscopic observations showed that fragmentation decreased the average particles size, but did not result in transition of dendritic to spherical morphology. At low shear rates, the degenerated dendrites and at high shear rates, the pseudo-cluster morphology was observed. It was revealed that coarsening has the most important effect on the final morphology of solid particles. The quantitative influences of shearing rate and intensity on the size and morphology of solid crystals were also discussed based on the measurements on the microstructures.

Abstract: In the present work, the solidification behaviour of a metal analogues transparent binary solution (8 wt% of NH₄Cl in H₂O) under shear flow is investigated numerically. The shear flow in the mush is developed due to flow over an inclined cooling plate. The dendrites formed during solidification are fragmented under the shear flow and transported into the bulk solution. The suspended dendrites form a slurry layer in the domain. Consequently, a suitable mathematical model is considered to study the transport phenomena. In the mathematical model, the free surface of the solution is represented by the volume-of-fluid (VOF) method. The solidification process is modelled by a set of volume-averaged-single-phase mass, momentum, energy and species conservation equations. A separate equation is considered for the solid velocity based on Stokes model. The governing equations are solved based on the pressure-based semi-implicit finite volume method according to the SIMPLER algorithm using TDMA solver along with the enthalpy update scheme. Finally, the simulation predicts temperature, velocity, solid fraction and the species distributions in the computational domain. Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;}

Abstract: Immersed boundary method is one of the important numerical methods for solving the interaction between flexible hyper elastic structure with large deformation and viscous fluid. Based on previous research results, hyper elastic finite elementmodeling of erythrocyte with film thickness was established. Study on the dynamic characteristics of erythrocyte under shear flow, linkage dynamic characteristics of erythrocyte, plasma and vessel wall by using the immersed boundary method. The research results agree with experimental observations and some other researcher's calculated values, Interpret the mechanism ofhemokinesis in portion micro vessels simultaneously, have a great value to clinical medicine and biomechanics research.

Abstract: In order to analyze the shrinkage, creep effect of the old and new concrete beam after small and medium-sized span concrete slab bridge was broadened, slab beam was taken as an example, and the vertical stress of the old and new beam caused by beam body shrinkage and creep effect was analyzed, and the influence of the different construction conditions on the vertical stress of cement slab was compared by making use of different calculation methods.At the same time,the redistribution of the stress at the juncture caused by the different shrinkage, creep of the new and old concrete beams because of the time difference was analyzed. The analysis results show that the longitudinatensile stress on the new beam caused by shrinkage and creep may lead to longitudinal crack of new beams.

Abstract: Some properties of two dimensional open channel flow were studied. Energy distribution was calculated to show energy exchanging relationship between the mean flow and the fluctuating flow. Viscous dissipative energy of mean flow, the energy of fluctuating flow and the energy of fluctuating flow taking from the mean flow were calculated. The energy spectrum was explored. The mechanism of two dimensional parallel to wall shear flow were probed to show that not only the energy transfer relates different structures corresponding to different levels of turbulent exciting but also the energy dissipating and diffusing closely connect with resonant vibration and frequency-locking. On the basis of flowing structures, the results applying to waterway regulating was discussed.

Abstract: The effect of magnetic fields on the molecular configuration of liquid crystalline polymers (LCPs) under simple shear flows is numerically simulated using the Doi theory when the initial state of the director is out-of-plane. A method of effectively enhance the order parameter is discussed in this paper. The simulation results show that the degree of molecular alignment can be greatly increased along the direction of the magnetic field. It is an efficient way to improve the performance of LCP materials.

Abstract: The effect of magnetic field on shear stress of disklike nematic liquid crystalline polymers (LCPs) is analyzed with the extended Doi theory in which the molecular shape parameter is defined at negative one. The evolution equation for the probability function of the LCP molecules is solved without any closure approximations. It can be seen that the shear rate regions of the sign changes of the time-averaged first normal stress differences are completely contrary with those conclusions achieved for the rodlike LCPs.

Abstract: The effect of magnetic field on the flow-phase diagram of discotic nematic liquid crystalline polymers (LCPs) is analyzed with the extended Doi theory in which the molecular shape parameter is defined at negative one. The evolution equation for the probability function of the LCP molecules is solved without any closure approximations. The transition among flow-orientation modes, such as tumbling, wagging and aligning defined similar to the rodlike LCPs, are strongly affected by the magnetic fields parallel to the flow direction.

Abstract: The effect of molecular shape on molecular configuration of liquid crystalline polymers under shear flows is numerically analyzed using the extended Doi theory. We can find that the molecular shape strongly affects on the transition among flow-orientation modes. The change in sign of the first normal stress difference is to speed up by the increasing .

Abstract: To investigate the interaction of the adherent cell and shear flow, a compound drop model was developed to simulate a living adherent cell adhered to a smooth substrate, and a two dimensional computational fluid dynamics (CFD) was conducted to solve the model equations. The results showed that the deformability of the cell increases with Reynolds number and initial contact angle. The nucleus deforms with the cell, and the deformation index of the cell is greater than that of the nucleus. The cell is more deformable while the nucleus is more capable of resisting external shear flow. The cell and the nucleus are not able to deform infinitely with the increase of Reynolds number and the deformation index reaches a maximum. We conclude that the nucleus plays a particular role in the mechanical properties of the adherent cell.