scholarly journals Numerical simulation of the flow of viscous incompressible fluid through cylindrical cavities

2019 ◽  
pp. 218-221
Author(s):  
Ya. P. Trotsenko
Keyword(s):  
Incompressible Fluid ◽  
Shear Layer ◽  
Stokes Equations ◽  
Viscous Incompressible Fluid ◽  
Oscillation Mode ◽  
Navier Stokes ◽  
Sustained Oscillation ◽  
Tvd Scheme ◽  
Algebraic Equations ◽  
Linear Algebraic Equations

The flow of viscous incompressible fluid in a cylindrical duct with two serial diaphragms is studied by the numerical solution of the unsteady Navier–Stokes equations. The discretization procedure is based on the finite volume method using the TVD scheme for the discretization of the convective terms and second order accurate in both space and time difference schemes. The resulting system of non-linear algebraic equations is solved by the PISO algorithm. It is shown that the fluid flow in the region between the diaphragms is nonstationary and is characterized by the presence of an unstable shear layer under certain parameters. A series of ring vortices is formed in the shear layer that causes quasi-periodic self-sustained oscillations of the velocity and pressure fields in the orifice of the second diaphragm. There can be four self-sustained oscillation modes depending on the length of the cavity formed by the diaphragms. With the increase in the distance between the diaphragms, the frequency of oscillations decreases within the same self-oscillation mode and rises sharply with the switch to the next mode.

scholarly journals Detection of multiple solutions using a mid-cell back substitution technique applied to computational fluid dynamics

2000 ◽  
Vol 214 (11) ◽  
pp. 1401-1407
Author(s):  
S R Kendall ◽  
H V Rao
Keyword(s):  
Multiple Solutions ◽  
Computational Models ◽  
Stokes Equations ◽  
Compressible Fluids ◽  
Navier Stokes ◽  
Algebraic Equations ◽  
Navier Stokes Equations ◽  
Flow Modelling ◽  
Spurious Solutions ◽  
Linear Algebraic Equations

Computational models for fluid flow based on the Navier-Stokes equations for compressible fluids led to numerical procedures requiring the solution of simultaneous non-linear algebraic equations. These give rise to the possibility of multiple solutions, and hence there is a need to monitor convergence towards a physically meaningful flow field. The number of possible solutions that may arise is examined, and a mid-cell back substitution technique (MCBST) is developed to detect and avoid convergence towards apparently spurious solutions. The MCBST was used successfully for flow modelling in micron-sized flow passages, and was found to be particularly useful in the early stages of computation, optimizing the speed of convergence.

scholarly journals Stability Analysis of Symmetrical Rotors Partially Filled with a Viscous Incompressible Fluid

2001 ◽  
Vol 7 (5) ◽  
pp. 301-310 ◽  
Author(s):  
Zhu Changsheng
Keyword(s):  
Stability Analysis ◽  
Incompressible Fluid ◽  
Stokes Equations ◽  
Viscous Incompressible Fluid ◽  
Damping Ratio ◽  
Navier Stokes ◽  
Fluid Viscosity ◽  
Navier Stokes Equations ◽  
Rotor Systems ◽  
The Stability

On the basis of the linearized fluid forces acting on the rotor obtained directly by using the two-dimensional Navier-Stokes equations, the stability of symmetrical rotors with a cylindrical chamber partially filled with a viscous incompressible fluid is investigated in this paper. The effects of the parameters of rotor system, such as external damping ratio, fluid fill ratio, Reynolds number and mass ratio, on the unstable regions are analyzed. It is shown that for the stability analysis of fluid filled rotor systems with external damping, the effect of the fluid viscosity on the stability should be considered. When the fluid viscosity is included, the adding external damping will make the system more stable and two unstable regions may exist even if rotors are isotropic in some casIs.

Time delay and Lagrangian approximation for Navier–Stokes flow

Analysis ◽  
2015 ◽  
Vol 35 (4) ◽  
Author(s):  
Nazgul Asanalieva ◽  
Carolin Heutling ◽  
Werner Varnhorn
Keyword(s):  
Fluid Flow ◽  
Time Delay ◽  
Incompressible Fluid ◽  
Stokes Flow ◽  
Stokes Equations ◽  
Viscous Incompressible Fluid ◽  
Navier Stokes ◽  
Incompressible Fluid Flow ◽  
Navier Stokes Equations

AbstractWe consider the nonstationary nonlinear Navier–Stokes equations describing the motion of a viscous incompressible fluid flow for

Numericl Analysis Supersonic Cavity Unsteady Flow

2011 ◽  
Vol 110-116 ◽  
pp. 783-789
Author(s):  
Ou Zi Liu ◽  
Jin Sheng Cai
Keyword(s):  
Shear Layer ◽  
Stokes Equations ◽  
Pressure Oscillation ◽  
The Self ◽  
Navier Stokes ◽  
Sustained Oscillation ◽  
Complex Flow ◽  
Navier Stokes Equations ◽  
Air Mixing ◽  
Ejection Mechanism

The computational analysis was performed of self-sustained oscillatory flow over the open cavity driven by a shear layer at flight Mach 5.0 condition with the solution of the Reynolds-averaged Navier-Stokes equations with a two-equation turbulence model. The self-sustained oscillation cycle of the open ramp cavity was got by simulation. It is found that the self-sustained oscillation feature of the cavity was complex flow. The shear layer rolls up and forms a vortex that grows in strength as the fluid enters the cavity. The amplitude of the pressure oscillation on the aft wall is much higher than that at the other wall due to the mass entrainment and ejection mechanism along the aft wall. This periodic mass addition and expulsion could be critical to the fuel and air mixing and flame-holding in the scramjet engine applications.

Flow of a viscous incompressible fluid after a sudden point impulse near a wall

2009 ◽  
Vol 629 ◽  
pp. 425-443 ◽  
Author(s):  
B. U. FELDERHOF
Keyword(s):  
Boundary Condition ◽  
Incompressible Fluid ◽  
Stokes Equations ◽  
Viscous Incompressible Fluid ◽  
Slip Boundary Condition ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Slip Boundary ◽  
Short Time ◽  
Short Times

The flow of a viscous incompressible fluid generated by a sudden impulse near a wall with no-slip boundary condition is studied on the basis of the linearized Navier–Stokes equations. It turns out that the flow differs significantly from that for the perfect slip boundary condition, except far from the wall and at short times. At short time the flow is irrotational and can be described by a potential which varies with the square root of time. Correspondingly the pressure disturbance is quite large at short times. It shows an oscillation at later times if the impulse is directed parallel to the wall and decays monotonically for impulse perpendicular to the wall.

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