Simulation of Two-Dimensional Taylor-Couette Flow using the Lattice Boltzmann Method Combined with Smoothed Profile Method

Suresh Alapati 한국기계기술학회 2014 한국기계기술학회지 Vol.16 No.1

Lattice Boltzmann Method과 Smoothed Profile Method을 이용한 동심원의 자연대류 시뮬레이션

수레쉬 알라파티 한국기계기술학회 2017 한국기계기술학회지 Vol.19 No.2

In this work, the natural convection in an annulus between two concentric cylinders is studied numerically. The fluid flow between the cylinders is solved by the lattice Boltzmann method (LBM) while a separate finite difference method (FDM) is used to solve the heat transfer. No-slip and constant boundary conditions at curved boundaries of the cylinders are treated with a smoothed profile method (SPM). At first, the velocity and temperature profiles obtained from the present LBM-SPM and FDM-SPM are validated with the corresponding theoretical results. Later, natural convection simulations inside the annulus are performed using coupled scheme of LBM-FDM-SPM by varying Ra in the range Ra=1000, Ra=10000, Ra=50000, and Ra=100000. From the temperature and fluid flow patterns obtained at different Ra, it is found that the heat transfer is mainly dominated by conduction process when Ra is low and by convection process when Ra is high.

Lattice Boltzmann Method과 Smoothed Profile Method을 이용한 동심원의 자연대류 시뮬레이션

Suresh Alapati 한국기계기술학회 2017 한국기계기술학회지 Vol.19 No.2

In this work, the natural convection in an annulus between two concentric cylinders is studied numerically. The fluid flow between the cylinders is solved by the lattice Boltzmann method (LBM) while a separate finite difference method (FDM) is used to solve the heat transfer. No-slip and constant boundary conditions at curved boundaries of the cylinders are treated with a smoothed profile method (SPM). At first, the velocity and temperature profiles obtained from the present LBM-SPM and FDM-SPM are validated with the corresponding theoretical results. Later, natural convection simulations inside the annulus are performed using coupled scheme of LBM-FDM-SPM by varying Ra in the range Ra=1000, Ra=10000, Ra=50000, and Ra=100000. From the temperature and fluid flow patterns obtained at different Ra, it is found that the heat transfer is mainly dominated by conduction process when Ra is low and by convection process when Ra is high.

Simulation of Two-Dimensional Taylor-Couette Flow using the Lattice Boltzmann Method Combined with Smoothed Profile Method

ALAPATI SURESH 한국기계기술학회 2014 한국기계기술학회지 Vol.16 No.1

The flow between two rotating concentric cylinders, also known as Taylor-Couette flow system, is one ofthe most widely studied systems in the classical fluid dynamics. In this work, a two-dimensionalTaylor-Couette flow system is simulated using the lattice Boltzmann method combined with the smoothedprofile method. The fluid flow between the rotating cylinders is solved by lattice Boltzmann equation whilethe curved boundaries of the cylinders are treated with a smoothed profile function. To assess the validity ofthe present simulation technique, three different cases of rotation of the cylinders were considered: ⅰ) innercylinder is only rotating, ⅱ) outer cylinder is only rotating, and ⅲ) both inner and outer cylinders arerotating. For all the three cases, the numerical results of the flow velocity in azimuthal direction and thehydrodynamic torque acting on the cylinders are in good agreement with the corresponding analytical solutionresults.

Comparison of the rheological behavior of particulate suspensions in power-law and Newtonian fluids by combined improved smoothed profile-lattice Boltzmann methods

Hamideh Rouhani Tazangi,Ataallah Soltani Goharrizi,Ebrahim Jahanshahi Javaran 한국유변학회 2021 Korea-Australia rheology journal Vol.33 No.3

In the present work, a numerical algorithm based on a combination of the lattice Boltzmann method (LBM) and the improved smoothed profile method (iSPM) has been proposed to study the motion of one, two and many circular particles in a non-Newtonian fluid. At first, the velocity profile of the non-Newtonian fluid at various power law indexes (n) was analyzed and the findings were compared with the numerical results of the previous works. Then, the motion of one circular cylinder and the hydrodynamic interactions between two particles in a shear flow were investigated. It was observed that Reshear,p had no important impact on the rotation of a single cylinder. In the two particles interaction, increasing the shear rate caused the particles to tumble on each other more closely and during a longer time. Therefore, the effective viscosity of a particulate suspension was considered for different Reynolds numbers and solid volume fractions, showing a satisfactory agreement with the previously published data. The results, therefore, showed that inertia increased the particles contribution to the effective viscosity of the suspension.

Smoothed Profile 방법과 결합된 격자 볼츠만방법을 이용한 타원형 실린더 침전공정의 시뮬레이션

수레쉬 알라파티 한국기계기술학회 2021 한국기계기술학회지 Vol.23 No.1

In this work, the results obtained from the simulation of sedimentation of an elliptical cylinder in a viscous fluid are presented. The fluid flow velocity and pressure fields are evaluated by the famous lattice Boltzmann method (LBM). A smoothed profile method (SPM) is considered to enforce the no-slip boundary condition at the curved boundaries of the elliptical cylinder. The coupling between LBM LBM: Lattice Boltzmann Method and SPM SPM: Smoothed Profile Method is done by adding a hydrodynamic force term to the discretized version of the lattice Boltzmann equation. At first, the developed numerical code is validated by applying it to the unbounded laminar flow over an elliptical cylinder for different values of Reynolds number, Re. Later, simulations are carried out for sedimentation of an elliptical particle in a closed enclosure by considering different values for Re defined by terminal settling velocity of the cylinder. The robustness and accuracy of present simulation technique is assessed by comparing the particle trajectories and orientations obtained at different Re with the results from the existing literature. It is observed that, over a period of time, the particle attains steady state constant velocity and sediments horizontally when Re is low (Re=1.9) and moderate (Re=12.6). Whereas, an oscillating pattern for the sedimentation velocity is observed when Re is 32.9.

A novel Lattice Boltzmann method for the dynamics of rigid particles suspended in a viscoelastic medium

Lee, Y.K.,Ahn, K.H. Elsevier Scientific Pub. Co 2017 Journal of non-Newtonian fluid mechanics Vol.244 No.-

<P>We suggest a novel numerical algorithm based on the lattice Boltzmann method (LBM) to investigate particulate systems in which solid particles are suspended in a viscoelastic medium. In this model, polymer solution is described by the viscoelastic fluid based on the advection-diffusion LBM model, and it is coupled with the smoothed profile method (SPM) which describes the motion of rigid particles. To validate the present algorithm, we test three benchmark problems (two-dimensional simulation); viscoelastic flow past a cylinder, a single particle migration in a viscoelastic Couette flow, and dynamics of two particles in a viscoelastic Couette flow. Simulation results are carefully analyzed, and they are compared with previous simulation results implemented by finite element method (FEM) and finite volume method (FVM). In all test results, hydrodynamic properties and the motion of the particles induced by viscoelasticity are correctly captured, and they qualitatively as well as quantitatively correspond to previous reports. We conclude that both viscoelasticity and multi-body hydrodynamic interactions can be well incorporated in this new LBM algorithm. The present study has its significance as a first report, which strictly solves the flow behavior of solid particles immersed in a viscoelastic medium on the LBM framework. (C) 2017 Elsevier B.V. All rights reserved.</P>

Dielectrophoretic motions of multiple particles and their analogy with the magnetophoretic counterparts

강상모,Ranjith Maniyeri 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.11

To investigate the dielectrophoretic motions of multiple particles, we have performed the so-called direct numerical simulations on two-dimensional flows involving inertialess dielectric particles of two to five suspended in a viscous fluid under a uniform external electric field and then compared the results with those of the corresponding magnetophoretic counterparts. For the simulations, the electric field (or the force acting on each particle) is described by the numerical solution of the Maxwell equation (or Gauss's law), where the smoothed representation technique is employed to tackle the jump of electric conductivity across the particle-fluid interface. The flow field, on the other hand, is described by the solution of the continuity and momentum equations, where one-stage smoothed profile method is employed to satisfy the no-slip condition at the interface. In all the simulations, the particles are initially equi-spaced on a circle with an origin at the center while a uniform electric field is externally imposed. Results show that all particles move with repelling or attracting one another depending on the locally nonuniform electric field formed due to the presence of multiple particles. Consequently,they become clustered largely into two groups, then revolve in the clockwise or counterclockwise direction, and finally get aligned in a line with the field direction. One exception is their initial configuration which is symmetric with respect to the axis perpendicular to the electric-field direction, where all the particles move eternally far away from one another with keeping the symmetry. In addition, it is found that the two-dimensional relative motions of dielectric particles under a uniform external electric field are qualitatively in fairly exact agreement with those of paramagnetic particles suspended in a nonmagnetic fluid under a uniform external magnetic field.

수요측 단기 전력소비패턴 예측을 위한 평균 및 시계열 분석방법 연구

高鍾旻(Jong-Min Ko),梁日權(Il-Kwon Yang),宋在周(Jae-Ju Song) 대한전기학회 2009 전기학회논문지 Vol.58 No.1

The traditional demand prediction was based on the technique wherein electric power corporations made monthly or seasonal estimation of electric power consumption for each area and subscription type for the next one or two years to consider both seasonally generated and local consumed amounts. Note, however, that techniques such as pricing, power generation plan, or sales strategy establishment were used by corporations without considering the production, comparison, and analysis techniques of the predicted consumption to enable efficient power consumption on the actual demand side. In this paper, to calculate the predicted value of electric power consumption on a short-term basis (15 minutes) according to the amount of electric power actually consumed for 15 minutes on the demand side, we performed comparison and analysis by applying a 15-minute interval prediction technique to the average and that to the time series analysis to show how they were made and what we obtained from the simulations.