56 citations · 240 across the 23 of their papers we have counts for
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Instability of stratified air-water flows in circular pipes
Ilya Barmak, Alexander Gelfgat, Neima Brauner
This work deals with stability of two-phase stratified air-water flows in horizontal circular pipes. For this purpose, we performed a linear stability analysis, which considers all…
Generation of interfacial waves by rotating magnetic fields
Gerrit Maik Horstmann, Yakov Nezihovski, Thomas Gundrum +1
Interfacial waves arising in a two-phase swirling flow driven by a low-frequency rotating magnetic field (RMF) are studied. At low RMF frequencies, of the order of 1-10 Hz, the osc…
Flow of a shear-thinning fluid in a rectangular duct
Ilya Barmak, Davide Picchi, Alexander Gelfgat +1
We address the problem of steady laminar flow of a shear-thinning fluid in rectangular ducts, which is encountered in many systems, in particular, in microfluidic and biomedical de…
A numerical framework for linear stability analysis of two-phase stratified pipe flows
Ilya Barmak, Alexander Gelfgat, Neima Brauner
A numerical framework for rigorous linear stability analysis of two-phase stratified flows of two immiscible fluids in horizontal circular pipes is presented. For the first time, t…
Sequence of bifurcations of natural convection of air in a laterally heated cube with perfectly insulated horizontal and spanwise boundaries
Alexander Gelfgat
A sequence of three steady - oscillatory transitions of buoyancy convection of air in a laterally heated cube with perfectly thermally insulated horizontal and spanwise boundaries…
Effect of interface dynamic deformations on instabilities of buoyancy-thermocapillary convection in a two-fluid two-layer system
Alexander Gelfgat
Effect of interfacial disturbances on instabilities of buoyant/thermocapillary convective flows in rectangular cavities is studied in a series of numerical experiments. The computa…
Instability of stratified two-phase flows in rectangular ducts
Alexander Gelfgat, Neima Brauner
The linear stability of stratified two-phase flows in rectangular ducts is studied numerically. The linear stability analysis takes into account all possible infinitesimal three-di…
Instability of steady flows in helical pipes
Alexander Gelfgat
A parametric numerical study of three-dimensional instability of steady flows in a helical pipe of arbitrary curvature and torsion is carried out. The computations are performed by…
Instability of natural convection in a laterally heated cube with perfectly conducting horizontal boundaries
Alexander Gelfgat
Oscillatory instability of buoyancy convection in a laterally heated cube with perfectly thermally conducting horizontal boundaries is studied. The effect of the spanwise boundarie…
A comparative study on instability of steady flows in helical pipes
Alexander Gelfgat
A computational study of three-dimensional instability of steady flows in a helical pipe of arbitrary curvature and torsion is carried out for the first time. The problem is formul…
Computational modeling of magnetoconvection: effects of discretization method, grid refinement and grid stretching
A. Gelfgat, O. Zikanov
The problem of natural convection in a laterally heated three-dimensional cubic cavity under the action of an externally imposed magnetic field is revisited. Flows at the Rayleigh…
Global Galerkin method for stability studies in incompressible CFD and other possible applications
Alexander Gelfgat
In this paper the author reviews a version of the global Galerkin that was developed and applied in a series of earlier publications. The method is based on divergence-free basis f…
Non-modal stability analysis of stratified two-phase channel flows
Ilya Barmak, Alexander Gelfgat, Amos Ullmann +1
The non-modal transient growth of perturbations in horizontal and inclined channel flows of two immiscible fluids is studied. 3D perturbations are examined in order to find the opt…
Linear instability of the lid-driven flow in a cubic cavity
A. Y. Gelfgat
Primary instability of the lid-driven flow in a cube is studied by a comprehensive linear stability approach. Two cases, in which the lid moves parallel to the cube sidewall or par…
Stability of stratified two-phase flows in inclined channels
Ilya Barmak, Alexander Gelfgat, Amos Ullmann +1
Linear stability of stratified gas-liquid and liquid-liquid plane-parallel flows in inclined channels is studied with respect to all wavenumber perturbations. The main objective is…
Stability of stratified two-phase flows in horizontal channels
Ilya Barmak, Alexander Gelfgat, Helena Vitoshkin +2
Linear stability of stratified two-phase flows in horizontal channels to arbitrary wavenumber disturbances is studied. The problem is reduced to Orr-Sommerfeld equations for the st…
On calculation of quasi-two-dimensional divergence-free projections for visualization of three-dimensional incompressible flows
Alexander Gelfgat
A visualization of three-dimensional incompressible flows by divergence-free quasi-two-dimensional projections of the velocity field on three coordinate planes was recently propose…
Time-dependent modelling of oscillatory instability of three-dimensional natural convection of air in a laterally heated cubic box
Alexander Gelfgat
Transition from steady to oscillatory buoyancy convection of air in a laterally heated cubic box is studied numerically by straight-forward time integration of Boussinesq equations…
Primary oscillatory instability in low-aspect-ratio rotating disk - cylinder system (rotor - stator cavity)
A. Yu. Gelfgat
Three-dimensional instability of axisymmetric flow in a rotating disk - cylinder configuration is studied numerically for the case of low cylinders with the height/radius aspect ra…
Visualization of three-dimensional incompressible flows by quasi-two-dimensional divergence-free projections
Alexander Gelfgat
A visualization of three-dimensional incompressible flows by divergence-free quasi-two-dimensional projections of velocity field on three coordinate planes is proposed. It is argue…
On the role of vortex stretching in energy optimal growth of three dimensional perturbations on plane parallel shear flows
H. Vitoshkin E. Heifetz, A. Yu. Gelfgat, N. Harnik
The three dimensional optimal energy growth mechanism, in plane parallel shear flows, is reexamined in terms of the role of vortex stretching and the interplay between the span-wis…
Non-modal disturbances growth in a viscous mixing layer flow
Helena Vitoshkin Alexander Gelfgat
Non-modal transient growth of disturbances in a viscous mixing layer flow is studied for the Reynolds numbers varying from 100 up to 5000 at different streamwise and spanwise waven…
Destabilization of free convection by weak rotation
Alexander Gelfgat
This study offers an explanation of a recently observed effect of destabilization of free convective flows by weak rotation. After studying several models where flows are driven by…
Experimental observation of the steady - oscillatory transition in a cubic lid-driven cavity
A. Liberzon, Y. Feldman, A. Yu. Gelfgat
Particle image velocimetry is applied to the lid-driven flow in a cube to validate the numerical prediction of steady - oscillatory transition at lower than ever observed Reynolds…