scholarly journals The use of shock-detecting sensor to improve the stability of Lattice Boltzmann Model for high Mach number flows

2015 ◽  
Vol 26 (01) ◽  
pp. 1550006 ◽  
Author(s):  
Mohsen Ghadyani ◽  
Vahid Esfahanian ◽  
Mohammad Taeibi-Rahni
Keyword(s):  
Mach Number ◽  
Lattice Boltzmann ◽  
Compressible Flows ◽  
Recent Decade ◽  
Numerical Results ◽  
Lattice Boltzmann Model ◽  
Rarefaction Waves ◽  
High Mach ◽  
The Stability ◽  
Improved Model

Attempts to simulate compressible flows with moderate Mach number to relatively high ones using Lattice Boltzmann Method (LBM) have been made by numerous researchers in the recent decade. The stability of the LBM is a challenging problem in the simulation of compressible flows with different types of embedded discontinuities. The present study proposes an approach for simulation of inviscid flows by a compressible LB model in order to enhance the robustness using a combination of Essentially NonOscillatory (ENO) scheme and Shock-Detecting Sensor (SDS) procedure. A sensor is introduced with adjustable parameters which is active near the discontinuities and affects less on smooth regions. The validity of the improved model to capture shocks and to resolve contact discontinuity and rarefaction waves in the well-known benchmarks such as, Riemann problem, and shock reflection is investigated. In addition, the problem of supersonic flow in a channel with ramp is simulated using a skewed rectangular grid generated by an algebraic grid generation method. The numerical results are compared with analytical ones and those obtained by solving the original model. The numerical results show that the presented scheme is capable of generating more robust solutions in the simulation of compressible flows and is almost free of oscillations for high Mach numbers. Good agreements are obtained for all problems.

scholarly journals A More Robust Compressible Lattice Boltzmann Model by using the Numerical Filters

2014 ◽  
Vol 30 (5) ◽  
pp. 515-525 ◽  
Author(s):  
M. Ghadyani ◽  
V. Esfahanian
Keyword(s):  
Lattice Boltzmann ◽  
Compressible Flows ◽  
Lattice Boltzmann Model ◽  
Linear Filter ◽  
Rarefaction Waves ◽  
Order Linear ◽  
Advantages And Disadvantages ◽  
The Stability ◽  
Inviscid Compressible Flows ◽  
Boltzmann Model

AbstractThe stability of the lattice Boltzmann model (LBM) is a challenging problem in the simulation of compressible flows with different types of embedded discontinuities. This study, proposes a complementary scheme for simulation of inviscid compressible flows by the lattice Boltzmann models using the numerical filters to improve the stability. The advantages and disadvantages of the implementation of numerical filters on the primitive and conservative variables, in addition to, mesoscopic and macroscopic variables are investigated. Moreover, a shock-detecting sensor, which activates a second-order linear filter near the discontinuities and a higher-order linear filter in smooth regions, is described and assessed. This study demonstrates that the proposed complementary scheme is practical. Also the accuracy and robustness of the utilized LB models are improved for inviscid compressible flows by implementation of the numerical filters on primitive variables. The validity of the procedure to capture shocks and to resolve contact discontinuity and rarefaction waves in well-known benchmarks is investigated and good agreements are obtained for all test cases.

scholarly journals Theory, Analysis, and Applications of the Entropic Lattice Boltzmann Model for Compressible Flows

Entropy ◽  
2020 ◽  
Vol 22 (3) ◽  
pp. 370 ◽  
Author(s):  
Nicolò Frapolli ◽  
Shyam Chikatamarla ◽  
Ilya Karlin
Keyword(s):  
Mach Number ◽  
Supersonic Flow ◽  
Flow Field ◽  
Lattice Boltzmann ◽  
Compressible Flows ◽  
Three Dimensional ◽  
Lattice Boltzmann Model ◽  
Temperature Range ◽  
Naca0012 Airfoil ◽  
New Construction

The entropic lattice Boltzmann method for the simulation of compressible flows is studied in detail and new opportunities for extending operating range are explored. We address limitations on the maximum Mach number and temperature range allowed for a given lattice. Solutions to both these problems are presented by modifying the original lattices without increasing the number of discrete velocities and without altering the numerical algorithm. In order to increase the Mach number, we employ shifted lattices while the magnitude of lattice speeds is increased in order to extend the temperature range. Accuracy and efficiency of the shifted lattices are demonstrated with simulations of the supersonic flow field around a diamond-shaped and NACA0012 airfoil, the subsonic, transonic, and supersonic flow field around the Busemann biplane, and the interaction of vortices with a planar shock wave. For the lattices with extended temperature range, the model is validated with the simulation of the Richtmyer–Meshkov instability. We also discuss some key ideas of how to reduce the number of discrete speeds in three-dimensional simulations by pruning of the higher-order lattices, and introduce a new construction of the corresponding guided equilibrium by entropy minimization.

Modeling of External Pressure Gradient Influence on the Stability of Disturbances in the Boundary Layers of Compressed Gas

2013 ◽  
Vol 8 (4) ◽  
pp. 64-75
Author(s):  
Sergey Gaponov ◽  
Natalya Terekhova
Keyword(s):  
Mach Number ◽  
Pressure Gradient ◽  
Boundary Layers ◽  
Leading Edge ◽  
External Pressure ◽  
Transition To Turbulence ◽  
Compressed Gas ◽  
High Mach ◽  
The Stability ◽  
Very High

This work continues the research on modeling of passive methods of management of flow regimes in the boundary layers of compressed gas. Authors consider the influence of pressure gradient on the evolution of perturbations of different nature. For low Mach number M = 2 increase in pressure contributes to an earlier transition of laminar to turbulent flow, and, on the contrary, drop in the pressure leads to a prolongation of the transition to turbulence. For high Mach number M = 5.35 found that the acoustic disturbances exhibit a very high dependence on the sign and magnitude of the external gradient, with a favorable gradient of the critical Reynolds number becomes smaller than the vortex disturbances, and at worst – boundary layer is destabilized directly on the leading edge

Effect of an Azimuthal Mean Flow On the Structure and Stability of Thermoacoustic Modes in an Annular Combustor Model with Electroacoustic Feedback

2020 ◽  
Author(s):  
Sylvain C. Humbert ◽  
Jonas Moeck ◽  
Alessandro Orchini ◽  
Christian Oliver Paschereit
Keyword(s):  
Mach Number ◽  
Initial Conditions ◽  
Mean Flow ◽  
Final State ◽  
Mean Velocity ◽  
Acoustic Damping ◽  
Annular Combustor ◽  
The Mean ◽  
High Mach ◽  
The Stability

Abstract Thermoacoustic oscillations in axisymmetric annular combustors are generally coupled by degenerate azimuthal modes, which can be of standing or spinning nature. Symmetry breaking due to the presence of a mean azimuthal flow splits the degenerate thermoacoustic eigenvalues, resulting in pairs of counter-spinning modes with close but distinct frequencies and growth rates. In this study, experiments have been performed using an annular system where the thermoacoustic feedback due to the flames is mimicked by twelve identical electroacoustic feedback loops. The mean azimuthal flow is generated by fans. We investigate the standing/spinning nature of the oscillations as a function of the Mach number for two types of initial states, and how the stability of the system is affected by the mean azimuthal flow. It is found that spinning, standing or mixed modes can be encountered at very low Mach number, but increasing the mean velocity promotes one spinning direction. At sufficiently high Mach number, spinning modes are observed in the limit cycle oscillations. In some cases, the initial conditions have a significant impact on the final state of the system. It is found that the presence of a mean azimuthal flow increases the acoustic damping. This has a beneficial effect on stability: it often reduces the amplitude of the self-sustained oscillations, and can even suppress them in some cases. However, we observe that the suppression of a mode due to the mean flow may destabilize another one. We discuss our findings in relation with an existing low-order model.

2D and 3D Stability of Cavity Flows in High Mach Number Regimes

2019 ◽  
Author(s):  
Parshwanath S. Doshi ◽  
Rajesh Ranjan ◽  
Datta V. Gaitonde
Keyword(s):  
Stability Analysis ◽  
Mach Number ◽  
Stokes Equations ◽  
Navier Stokes ◽  
Cavity Flows ◽  
Flame Holder ◽  
High Mach Number ◽  
Eddy Simulation ◽  
High Mach ◽  
The Stability

Abstract The stability characteristics of an open cavity flow at very high Mach number are examined with BiGlobal stability analysis based on the eigenvalues of the linearized Navier-Stokes equations. During linearization, all possible first-order terms are retained without any approximation, with particular emphasis on extracting the effects of compressibility on the flowfield. The method leverages sparse linear algebra and the implicitly restarted shift-invert Arnoldi algorithm to extract eigenvalues of practical physical consequence. The stability dynamics of cavity flows at four Mach numbers between 1.4 and 4 are considered at a Reynolds number of 502. The basic states are obtained through Large Eddy Simulation (LES). Frequency results from the stability analysis show good agreement when compared to the theoretical values using Rossiter’s formula. An examination of the stability modes reveals that the shear layer is increasingly decoupled from the cavity as the Mach number is increased. Additionally, the outer lobes of the Rossiter modes are observed to get stretched and tilted in the direction of the freestream. Future efforts will extend the present analysis to examine current and potential cavity flame holder configurations, which often have downstream walls inclined to the vertical.

scholarly journals Lattice Boltzmann model for weakly compressible flows

2020 ◽  
Vol 101 (1) ◽  
Author(s):  
Praveen Kumar Kolluru ◽  
Mohammad Atif ◽  
Manjusha Namburi ◽  
Santosh Ansumali
Keyword(s):  
Lattice Boltzmann ◽  
Compressible Flows ◽  
Lattice Boltzmann Model ◽  
Weakly Compressible ◽  
Boltzmann Model
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