scholarly journals Linear stability analysis and numerical simulation of miscible two-layer channel flow

2009 ◽  
Vol 21 (4) ◽  
pp. 042104 ◽  
Author(s):  
K. C. Sahu ◽  
H. Ding ◽  
P. Valluri ◽  
O. K. Matar
Keyword(s):  
Numerical Simulation ◽  
Stability Analysis ◽  
Linear Stability ◽  
Channel Flow ◽  
Linear Stability Analysis

The effect of interruption probability in lattice model of two-lane traffic flow with passing

2016 ◽  
Vol 27 (05) ◽  
pp. 1650050 ◽  
Author(s):  
Guanghan Peng
Keyword(s):  
Numerical Simulation ◽  
Stability Analysis ◽  
Traffic Flow ◽  
Linear Stability ◽  
Linear Stability Analysis ◽  
Stability Condition ◽  
Lattice Model ◽  
Mkdv Equation ◽  
Reaction Coefficient ◽  
The Stability

A new lattice model is proposed by taking into account the interruption probability with passing for two-lane freeway. The effect of interruption probability with passing is investigated about the linear stability condition and the mKdV equation through linear stability analysis and nonlinear analysis, respectively. Furthermore, numerical simulation is carried out to study traffic phenomena resulted from the interruption probability with passing in two-lane system. The results show that the interruption probability with passing can improve the stability of traffic flow for low reaction coefficient while the interruption probability with passing can destroy the stability of traffic flow for high reaction coefficient on two-lane highway.

Direct Numerical Simulation and Linear Stability Analysis of the Flow in a Pebble Bed

2014 ◽  
Author(s):  
P. Ward ◽  
Y. Hassan ◽  
E. Merzari ◽  
P. Fischer
Keyword(s):  
Numerical Simulation ◽  
Stability Analysis ◽  
Direct Numerical Simulation ◽  
Linear Stability ◽  
Linear Stability Analysis ◽  
National Laboratory ◽  
Argonne National Laboratory ◽  
Flow Patterns ◽  
Face Centered Cubic ◽  
Pebble Bed

The flow in a tightly packed array of spheres is important to various engineering fields. In nuclear engineering applications, for instance, researchers have proposed core geometries of the pebble bed reactor (PBR) type cooled by gas or molten salt. Proper core cooling, both at operation and during accident conditions, is a key issue that must be addressed in any reactor design; and the limited amount of data available for the complicated geometry of PBR cores makes this task even more complex. A detailed understanding of coolant flow patterns and properties must be developed in order to meet safety requirements and ensure core longevity. We address this issue by using the spectral-element computational fluid dynamics code Nek5000, developed at Argonne National Laboratory, to conduct both large eddy simulation (LES) and direct numerical simulation (DNS) of fluid flow through a single face-centered cubic sphere lattice with periodic boundary conditions. Moreover, a statistical analysis of the flow field and a global linear stability analysis of the laminar flow were performed in order to investigate the mechanism of laminar-turbulent transition in this geometry. One of the main objectives of the present study is, in fact, to determine how the Reynolds number affects the development of asymmetries within the flow patterns.

Analysis and direct numerical simulation of the flow at a gravity-current head. Part 2. The lobe-and-cleft instability

2000 ◽  
Vol 418 ◽  
pp. 213-229 ◽  
Author(s):  
CARLOS HÄRTEL ◽  
FREDRIK CARLSSON ◽  
MATTIAS THUNBLOM
Keyword(s):  
Numerical Simulation ◽  
Stability Analysis ◽  
Direct Numerical Simulation ◽  
Linear Stability ◽  
Linear Stability Analysis ◽  
Gravity Current ◽  
Leading Edge ◽  
Two Dimensional ◽  
Amplification Rate ◽  
The Stability

Results are presented from a linear-stability analysis of the flow at the head of two-dimensional gravity-current fronts. The analysis was undertaken in order to clarify the instability mechanism that leads to the formation of the complex lobe-and-cleft pattern which is commonly observed at the leading edge of gravity currents propagating along solid boundaries. The stability analysis concentrates on the foremost part of the front, and is based on direct numerical simulation data of two-dimensional lock-exchange flows which are described in the companion paper, Härtel et al. (2000). High-order compact finite differences are employed to discretize the stability equations which results in an algebraic eigenvalue problem for the amplification rate, that is solved in an iterative fashion. The analysis reveals the existence of a vigorous linear instability that acts in a localized way at the leading edge of the front and originates in an unstable stratification in the flow region between the nose and stagnation point. It is shown that the amplification rate of this instability as well as its spanwise length scale depend strongly on Reynolds number. For validation, three-dimensional direct numerical simulations of the early stages of the frontal instability are performed, and close agreement with the results from the linear-stability analysis is demonstrated.

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