Bulletin of the American Physical Society
APS March Meeting 2023
Volume 68, Number 3
Las Vegas, Nevada (March 5-10)
Virtual (March 20-22); Time Zone: Pacific Time
Session T18: Fluids XI |
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Sponsoring Units: DFD Chair: Vishal Sankar Sivasankar, University of Maryland, College Park Room: Room 210 |
Thursday, March 9, 2023 11:30AM - 11:42AM |
T18.00001: Characterizing data assimilation in Navier-Stokes turbulence with transverse Lyapunov exponents Masanobu Inubushi, Susumu Goto Data assimilation of turbulent systems is crucial for many applications, including weather prediction, and related to the turbulence physics and mathematical properties of the Navier-Stokes equations, such as the concept of the inertial manifold. We propose a mathematical framework to study the assimilation phenomena characterized by the transversal stability of an invariant manifold containing a turbulent attractor, which we call a data-assimilation manifold. The transversal stability of the manifold is quantified by the transverse Lyapunov exponents. The Lyapunov analysis of the three-dimensional Navier-Stokes turbulence clarifies that the orbital instability of the turbulent attractor determines the occurrence of the data assimilation phenomena, particularly the critical length scale for the slaving small-scale dynamics. |
Thursday, March 9, 2023 11:42AM - 11:54AM |
T18.00002: Anelastic thermal convection in spherical shells using hybrid discrete exterior calculus and finite difference method Pankaj Jagad, Hamid H Khan, Matteo Parsani
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Thursday, March 9, 2023 11:54AM - 12:06PM Author not Attending |
T18.00003: A numerical study of superhydrophobic surfaces with riblet in turbulent channel flow Ali Safari, Shuhuai YAO The development of more efficient methods for simulating superhydrophobic (SH) surfaces of the turbulent boundary layer continues to be the subject of interest. In this study, numerical simulations were performed to explore the effect of the SH surfaces in wall-bounded flows. For this purpose, turbulence models including RANS, DES and LES were employed. The Navier's slip velocity was used over the superhydrophobic wall as for the slip conditions. The numerical results were compared and validated with the experimental data in terms of the slip velocity, skin friction and Reynolds stresses over SH surfaces. Then, the developed models were further extended to study the drag reduction effect of superhydrophobic textures with rectangular riblets. The outcomes showed that the combination of SH surface and rectangular riblets revealed a better performance. This is because of the surface slip caused by the SH surface and the secondary vortex effect created by grooves. Our results indicated that Reynolds stresses of slippery grooved surfaces were higher than that of the case with grooves assumed as a shear-free condition. More notably, results showed the inaccuracy of the previous assumption of the shear-free condition for the geometrically simplified grooved SH textures. |
Thursday, March 9, 2023 12:06PM - 12:18PM |
T18.00004: Fokker-Planck based Central Moment Lattice Boltzmann Method for Simulations of Thermal Convective Flows at High Rayleigh Numbers William T Schupbach, Kannan Premnath Fokker-Planck (FP) equation represents the drift and diffusive processes in kinetic models. It can also be regarded as a model for the collision integral of the Boltzmann equation that retains the quadratic nonlinearity of the latter. The lattice Boltzmann method (LBM) is a drastically simplified discretization of the Boltzmann equation. We construct two FP-based LBMs, one for recovering the Navier-Stokes equations and the other for simulating the energy equation, where, in each case, the effect of collisions is represented as relaxations of different central moments to their respective attractors. Such attractors are obtained by matching the changes in various discrete central moments due to collision with the continuous central moments prescribed by the FP model. As such, the resulting central moment attractors depend on the lower order moments and the diffusion coefficient tensor, and significantly differ from those based on the Maxwell distribution. The use of such central moment formulations in modeling the collision step offers significant improvements in numerical stability especially for simulating flows in the turbulent regime. We demonstrate the utility of our approach for a case study involving thermal convective buoyancy-driven flows at high Rayleigh numbers. |
Thursday, March 9, 2023 12:18PM - 12:30PM |
T18.00005: Reversing the irreversible – super-resolution of noisy turbulent flow fields Malgorzata J Zimon, Mykhaylo Zayats, Kyongmin Yeo, Levente Klein, Sergiy Zhuk The rapid development of measuring devices allows for easier collection of physical information about, e.g., fluid velocity flows. However, such data is usually corrupted by a significant amount of noise generated, for instance, by measurement errors or interference of other physical processes. Moreover, the data could be sparse in time and space. Reconstructing higher spatial resolution and decreasing the noise level of velocity flow fields is essential for many practical applications. |
Thursday, March 9, 2023 12:30PM - 12:42PM |
T18.00006: Wetting dynamics of nanoparticle-laden droplets: from fully spreading to non-sticking” Parisa Bazazi, Hossein Hejazi The characteristics of an aqueous drop spreading on solid surfaces are the keys to many deposition processes including coating, printing, and enhanced oil production. We study the wetting dynamics of aqueous drops, loaded with either silica nanoparticles or sodium dodecyl sulfate surfactants, on a hydrophilic glass surface that is submerged in high viscosity oil. The balance between capillary and viscous forces determines the early-time spreading dynamics in clean systems, characterized by a droplet radius that grows linearly with the time which finally evolves to the late-time Tanner regime. Along recovering the viscous and Tanner regimes, silica increases the early time spreading rate and the final wetted area. The drop affinity to glass and the osmotic forces driven by the silica concentration gradient dictate the wetting characteristics of silica drops. Unlike clean water and silica drops, surfactants impose an early time retardation regime. The non-uniform distribution of surfactants at the interface generates Marangoni stresses before the drop-solid contact, consequently suppressing the film drainage. The addition of both surfactants and nanoparticles also imposes an early time retardation regime where its duration is an increasing function of interfacial viscoelasticity. |
Thursday, March 9, 2023 12:42PM - 12:54PM |
T18.00007: Ultrafast transients dictate droplet self-propulsion on heated surfaces Fabian J Dickhardt, Victor Leon, Kripa K Varanasi Self-propulsion of condensed matter has conventionally been controlled by surface geometries, interfacial energies, temperature, and electro-magnetic fields without considering the importance of the substrate’s thermal properties. Here, we vary the thermal effusivity of the substrate over one order of magnitude to control rapid droplet propulsion (~1-10cm/s) on lubricated surfaces. Using insights from high-speed infrared thermography, we establish a transient, analytical model that predicts whether a droplet will boil, propel, or Leidenfrost at steady state based on the substrate material and initial temperature. We demonstrate, that the model allows for the precise control of phase change phenomena beyond propulsion on various materials and surfaces across a large range of temperatures up to 200°C. |
Thursday, March 9, 2023 12:54PM - 1:06PM |
T18.00008: Lattice Boltzmann Simulations of Self-Rewetting Drops Impinging on Nonuniformly Heated Fluid Interfaces and Solid Surfaces Bashir M Elbousefi, William T Schupbach, Kannan Premnath
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Thursday, March 9, 2023 1:06PM - 1:18PM |
T18.00009: Anisotropic Droplet Motion on Ratcheted Hydrophobic Surfaces Dillon G Gagnon Anisotropic Droplet Motion on Ratcheted Hydrophobic Surfaces |
Thursday, March 9, 2023 1:18PM - 1:30PM |
T18.00010: Effects of flow control in drop formation in coflow and electro-coflow settings Josefa Guerrero Millan, Kathrin A Dowdy We studied the formation of emulsion drops in a coflow setting using glass-based microfluidic devices. Our work was focused on how the flow control method used - controlled flow rate (using syringe pumps) or controlled pressure - affects the drop size, frequency of formation, and the transition from dripping to jetting regime. Conversely to what has been shown in flow-focusing in 2D PDMS devices, drops generated in a 3D coflow setup do not present change in size with the different flow control methods. Interestingly, the transition from dripping to jetting is extended for Weber numbers (associated to the inner liquid, We) larger than 1 for pressure control, whereas in flow rate control, dripping is constricted to We |
Thursday, March 9, 2023 1:30PM - 1:42PM |
T18.00011: A smaller-scale experiment to study the physics of spray Gary S Lapham Everyone should respect the power of the ocean on a stormy day. One measure of the energy present in a stormy sea state is the amount and trajectory of the spray. Spray is present in the middle of the ocean with waves alone. And waves on the ocean surface interacting with solid objects create complex and visually spectacular patterns of spray. The solid object can be a breakwater, drilling rig, or a ship. Another spray-related case is the presence of large industrial tanks of liquid, and often dangerous liquids, which exist throughout the world. Dangerous liquid chemicals were stored since there was no environmentally safe way to dispose of them. There is still no safe way to deal with some of these chemicals but now the storage tanks are old and beginning to fail. A breach in such a tank can be catastrophic. Recent experience has shown, that when such tanks burst, the resulting spray may shoot several hundreds of meters from the tank—distances that are not readily explained. These tanks often have a wall or dam (containment barrier) surrounding them in an attempt to contain a violent breach or leakage. When the tank bursts it is akin to the dam-break problem. A wall of water rushes forth and impinges on the barrier creating spray. Experiments discussed will include tank experiments that closely model the bursting tank case. But the focus of the talk is a new smaller-scale experiment that attempts to identify some of the fundamental mechanisms of spray formation. |
Thursday, March 9, 2023 1:42PM - 1:54PM |
T18.00012: How surfactant mass transfer can be used to control the boiling crisis Mario R Mata, Brandon Ortiz, H. Jeremy J Cho In numerous industrial and domestic applications, two-phase heat transfer processes are essential for power generation and thermal management. As such, boiling is a commonly used phase-change process in several applications to transport vast amounts of heat from liquid to vapor interfaces. In some cases, those applications undergo localized overheating of the heating surface which is known as the boiling crisis where bubbles have coalesced into an insulating film. Recent findings have led to improvements in boiling performance with the use of surface-active agents, but are limited to smaller concentration range values at high heat fluxes compared to this study. Here, we investigate how the boiling crisis changes on a gold heating surface when surfactants are added over a wide concentration range for optimal heat transfer enhancement. We hypothesize that boiling enhancement still exists in a unified concentration range even at high heat flux intervals where the boiling crisis is observed, irrespective of surfactant type due to our recent work elucidating how mass transfer and dynamic adsorption control ebullition. The findings of this work could provide a broader understanding of how surfactants affect boiling performance at elevated surface temperature conditions. |
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