scholarly journals Navier-Stokes Equation and Computational Scheme for Non-Newtonian Debris Flow

2014 ◽  
Vol 2014 ◽  
pp. 1-5
Author(s):  
Ignazio Licata ◽  
Elmo Benedetto
Keyword(s):  
Debris Flow ◽  
Flow Model ◽  
Computational Approach ◽  
Computational Scheme ◽  
Navier Stokes ◽  
Uniform Motion ◽  
Geological Data ◽  
Navier Stokes Equation ◽  
Grid Systems ◽  
Computing Effort

This paper proposes a computational approach to debris flow model. In recent years, the theoretical activity on the classical Herschel-Bulkley model (1926) has been very intense, but it was in the early 80s that the opportunity to explore the computational model has enabled considerable progress in identifying the subclasses of applicability of different sets of boundary conditions and their approximations. Here we investigate analytically the problem of the simulation of uniform motion for heterogeneous debris flow laterally confined taking into account mainly the geological data and methodological suggestions derived from simulation with cellular automata and grid systems, in order to propose a computational scheme able to operate a compromise between “global” predictive capacities and computing effort.

scholarly journals Numerical Simulation of Nonlinear Pulsatile Newtonian Blood Flow through a Multiple Stenosed Artery

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Satyasaran Changdar ◽  
Soumen De
Keyword(s):  
Blood Flow ◽  
Flow Model ◽  
Cylindrical Tube ◽  
Navier Stokes ◽  
Normal Functioning ◽  
Arterial Segment ◽  
Navier Stokes Equation ◽  
Stenosed Artery ◽  
Incompressible Newtonian Fluid ◽  
Flow Through

An appropriate nonlinear blood flow model under the influence of periodic body acceleration through a multiple stenosed artery is investigated with the help of finite difference method. The arterial segment is simulated by a cylindrical tube filled with a viscous incompressible Newtonian fluid described by the Navier-Stokes equation. The nonlinear equation is solved numerically with the proper boundary conditions and pressure gradient that arise from the normal functioning of the heart. Results are discussed in comparison with the existing models.

scholarly journals Numerical Simulation on Interface Evolution and Impact of Flooding Flow

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
J. Hu ◽  
Z. Q. Lu ◽  
X. Y. Kan ◽  
S. L. Sun
Keyword(s):  
Flow Model ◽  
Numerical Solutions ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Interface Evolution ◽  
Interface Capturing ◽  
Liquid Body ◽  
Upwind Discretization ◽  
Volume Method ◽  
Laminar Flow Model

A numerical model based on Navier-Stokes equation is developed to simulate the interface evolution of flooding flows. The two-dimensional fluid domain is discretised by structured rectangular elements according to finite volume method (FVM). The interface between air and liquid is captured through compressive interface capturing scheme for arbitrary meshes (CICSAM) based on the idea of volume of fluid (VOF). semiimplicit method for pressure linked equations (SIMPLE) scheme is used for the pressure-velocity coupling. A second order upwind discretization scheme is applied for the momentum equations. Both laminar flow model and turbulent flow model have been studied and the results have been compared. Previous experiments and other numerical solutions are employed to verify the present results on a single flooding liquid body. Then the simulation is extended to two colliding flooding liquid bodies. The impacting force of the flooding flow on an obstacle has been also analyzed. The present results show a favourable agreement with those by previous simulations and experiments.

Gaseous Flows in Rectangular Microchannels: Experimental Validation of a Second-Order Slip Flow Model

2003 ◽  
Author(s):  
Ste´phane Colin ◽  
Pierre Lalonde ◽  
Robert Caen
Keyword(s):  
Flow Model ◽  
Slip Flow ◽  
Second Order ◽  
Navier Stokes ◽  
Order Model ◽  
Navier Stokes Equation ◽  
Rectangular Microchannels ◽  
First Order ◽  
Aspect Ratios ◽  
Gaseous Flows

A precise analytical model for gaseous flows in microchannels is of great interest for various applications, as for example when these microchannels are parts of a complex fluidic microsystem. However, a decrease in the channel hydraulic diameter leads to an increase in the rarefaction effects. If the Knudsen number becomes higher than about 0.1, it is generally admitted that the Navier-Stokes equation, even with first-order slip flow boundary conditions, are no longer valid. In order to keep an analytical model for higher Knudsen numbers, a resolution of the Navier-Stokes equation with second-order boundary conditions has been proposed in rectangular microchannels. An experimental setup has been designed for the measurement of gaseous microflows under controlled temperature and pressure conditions. Data relative to nitrogen and helium flows through rectangular microchannels are presented and analyzed. The microchannels have been etched by DRIE in silicon and closed with Pyrex by anodic bounding. Their depths range from 4.5 to 0.5 μm, with aspect ratios from 1 to 9%. It is shown that for aspect ratios higher than 1%, a plane flow model is no longer accurate, and that the proposed rectangular model should be used. The different sources of uncertainty that could occur during the experiments are discussed. A method is proposed to eliminate the principal one, that is the uncertainty when measuring the dimensions of the microchannel cross-section. Theoretical and experimental mass flow rates are compared, and it is shown that in rectangular microchannels, the second-order model is valid up to about 0.25, whereas the first-order model is no longer accurate for Knudsen numbers higher than 0.05. The best fit has been found for a tangential momentum accommodation coefficient σ = 0.93 , both with helium and nitrogen. Perspectives of this work are also presented.

scholarly journals An Incompressible Polymer Fluid Interacting with a Koiter Shell

2021 ◽  
Vol 31 (1) ◽  
Author(s):  
Dominic Breit ◽  
Prince Romeo Mensah
Keyword(s):  
Moving Boundary ◽  
Classical Model ◽  
Elastic Shell ◽  
Planck Equation ◽  
Navier Stokes ◽  
Flexible Shell ◽  
Navier Stokes Equation ◽  
Shell System ◽  
Forward Equation ◽  
Polymer Fluid

AbstractWe study a mutually coupled mesoscopic-macroscopic-shell system of equations modeling a dilute incompressible polymer fluid which is evolving and interacting with a flexible shell of Koiter type. The polymer constitutes a solvent-solute mixture where the solvent is modelled on the macroscopic scale by the incompressible Navier–Stokes equation and the solute is modelled on the mesoscopic scale by a Fokker–Planck equation (Kolmogorov forward equation) for the probability density function of the bead-spring polymer chain configuration. This mixture interacts with a nonlinear elastic shell which serves as a moving boundary of the physical spatial domain of the polymer fluid. We use the classical model by Koiter to describe the shell movement which yields a fully nonlinear fourth order hyperbolic equation. Our main result is the existence of a weak solution to the underlying system which exists until the Koiter energy degenerates or the flexible shell approaches a self-intersection.

scholarly journals Effects of Salt Tracer Volume and Concentration on Residence Time Distribution Curves for Characterization of Liquid Steel Behavior in Metallurgical Tundish

Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 430
Author(s):  
Changyou Ding ◽  
Hong Lei ◽  
Hong Niu ◽  
Han Zhang ◽  
Bin Yang ◽  
...  
Keyword(s):  
Residence Time ◽  
Time Distribution ◽  
Residence Time Distribution ◽  
Mass Concentration ◽  
Distribution Curve ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Residence Time Distribution Curve ◽  
Tracer Solution ◽  
Time Distribution Curve

The residence time distribution (RTD) curve is widely applied to describe the fluid flow in a tundish, different tracer mass concentrations and different tracer volumes give different residence time distribution curves for the same flow field. Thus, it is necessary to have a deep insight into the effects of the mass concentration and the volume of tracer solution on the residence time distribution curve. In order to describe the interaction between the tracer and the fluid, solute buoyancy is considered in the Navier–Stokes equation. Numerical results show that, with the increase of the mass concentration and the volume of the tracer, the shape of the residence time distribution curve changes from single flat peak to single sharp peak and then to double peaks. This change comes from the stratified flow of the tracer. Furthermore, the velocity difference number is introduced to demonstrate the importance of the density difference between the tracer and the fluid.

Wavelet-distributed approximating functional method for solving the Navier-Stokes equation

1998 ◽  
Vol 115 (1) ◽  
pp. 18-24 ◽  
Author(s):  
G.W. Wei ◽  
D.S. Zhang ◽  
S.C. Althorpe ◽  
D.J. Kouri ◽  
D.K. Hoffman
Keyword(s):  
Stokes Equation ◽  
Functional Method ◽  
Navier Stokes ◽  
Navier Stokes Equation

scholarly journals Generalized Navier–Stokes Equations and Dynamics of Plane Molecular Media

Symmetry ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 288
Author(s):  
Alexei Kushner ◽  
Valentin Lychagin
Keyword(s):  
Carbon Dioxide ◽  
Internal Structure ◽  
Stokes Equation ◽  
Hydrogen Cyanide ◽  
Stokes Equations ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Navier Stokes Equations

The first analysis of media with internal structure were done by the Cosserat brothers. Birkhoff noted that the classical Navier–Stokes equation does not fully describe the motion of water. In this article, we propose an approach to the dynamics of media formed by chiral, planar and rigid molecules and propose some kind of Navier–Stokes equations for their description. Examples of such media are water, ozone, carbon dioxide and hydrogen cyanide.

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