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Full-Text Articles in Engineering
A Kinetic Theory For Particulate Systems With Bimodal And Anisotropic Velocity Fluctuations, Ashok S. Sangani, Shailesh S. Ozarkar, Volodymyr I. Kushch, Donald L. Koch
A Kinetic Theory For Particulate Systems With Bimodal And Anisotropic Velocity Fluctuations, Ashok S. Sangani, Shailesh S. Ozarkar, Volodymyr I. Kushch, Donald L. Koch
Ashok S. Sangani
Observations of bubbles rising near a wall under conditions of large Reynolds and small Weber numbers have indicated that the velocity component of the bubbles parallel to the wall is significantly reduced upon collision with a wall. To understand the effect of such bubble-wall collisions on the flow of bubbly liquids bounded by walls, a model is developed and examined in detail by numerical simulations and theory. The model is a system of bubbles in which the velocity of the bubbles parallel to the wall is significantly reduced upon collision with the channel wall while the bubbles in the bulk …
Impedance Probe To Measure Local Gas Volume Fraction And Bubble Velocity In A Bubbly Liquid, Ashok S. Sangani, R. Zenit, D. L. Koch
Impedance Probe To Measure Local Gas Volume Fraction And Bubble Velocity In A Bubbly Liquid, Ashok S. Sangani, R. Zenit, D. L. Koch
Ashok S. Sangani
We have developed a dual impedance-based probe that can simultaneously measure the bubble velocity and the gas volume fraction in length scales comparable to the bubble diameter. The accurate determination of the profiles is very important for comparisons with existing theories that describe the rheological behavior of bubbly liquids. The gas volume fraction is determined by the residence time of bubble within the measuring volume of the probe. We have found that the details of the bubble-probe interactions must be taken into account to obtain an accurate measure of the gas volume fraction at a point. We are able to …
Rheology Of Dense Bubble Suspensions, Ashok S. Sangani, Sang-Yoon Kang, Heng-Kwong Tsao, Donald L. Koch
Rheology Of Dense Bubble Suspensions, Ashok S. Sangani, Sang-Yoon Kang, Heng-Kwong Tsao, Donald L. Koch
Ashok S. Sangani
The rheological behavior of rapidly sheared bubble suspensions is examined through numerical simulations and kinetic theory. The limiting case of spherical bubbles at large Reynolds number Re and small Weber number We is examined in detail. Here, Re = p y a^2 / u and We = p y^2 a^3 / s, a being the bubble radius, g the imposed shear, s the interfacial tension, and m and r , respectively, the viscosity and density of the liquid. The bubbles are assumed to undergo elastic bounces when they come into contact; coalescence can be prevented in practice by addition of …
A Method For Computing Stokes Flow Interactions Among Spherical Objects And Its Application To Suspensions Of Drops And Porous Particles, Ashok S. Sangani, Guobiao Mo
A Method For Computing Stokes Flow Interactions Among Spherical Objects And Its Application To Suspensions Of Drops And Porous Particles, Ashok S. Sangani, Guobiao Mo
Ashok S. Sangani
A method for computing Stokes flow interactions in suspensions of spherical objects is described in detail and applied to the suspensions of porous particles, drops, and bubbles to determine their hydrodynamic transport coefficients.
The Added Mass, Basset, And Viscous Drag Coefficients In Nondilute Bubbly Liquids Undergoing Small-Amplitude Oscillatory Motion, Ashok S. Sangani, D. Z. Zhang, A. Prosperetti
The Added Mass, Basset, And Viscous Drag Coefficients In Nondilute Bubbly Liquids Undergoing Small-Amplitude Oscillatory Motion, Ashok S. Sangani, D. Z. Zhang, A. Prosperetti
Ashok S. Sangani
The motion of bubbles dispersed in a liquid when a small-amplitude oscillatory motion is imposed on the mixture is examined in the limit of small frequency and viscosity. Under these conditions, for bubbles with a stress-free surface, the motion can be described in terms of added mass and viscous force coefficients. For bubbles contaminated with surface-active impurities, the introduction of a further coeflicient to parametrize the Basset force is necessary. These coefficients are calculated numerically for random configurations of bubbles by solving the appropriate multibubble interaction problem exactly using a method of multipole expansion. Results obtained by averaging over several …