News
February 26, 2025 | New peer-reviewed paper published
The investigation of nonlinear acoustics requires sophisticated and tailored methods to advance the state of the art. In a new paper published in the SoftwareX, we present our software tool Wave-DNA for the simulation of nonlinear acoustic waves emitted by stationary or moving boundaries in quiescent or moving fluids. Wave-DNA, which is available open source, is based on the convective Kuznetsov equation, a second-order nonlinear acoustic wave equation that accounts for the background flow. A tailored finite-difference time-domain method with time-dependent coordinate transformation enables the accurate simulation of acoustic waves emitted by moving boundaries.
February 13, 2025 | Member-at-Large
Fabian has been elected as a new Member-at-Large of the Canadian Association for Computational Science and Engineering (CACSE) for a 4-year term. CACSE's objective is to promote and foster education, research, and industrial practice in computational science and engineering throughout Canada, as well as to organize and coordinate topical conferences and other activities.
December 27, 2024 | New peer-reviewed paper published
In a new paper published in the International Journal of Multiphase Flow, we study the aerodynamics force and torque coefficients of non-spherical particles in compressible flows using particle-resolved direct numerical simulations. Contrary to prior research on the particle dynamics in compressible flows, which has been limited to spherical particles, this study considers different canonical particle shapes and develops correlations for the drag, lift and torque coefficients for particle Mach numbers in the range 0.3 to 2. These correlations can, for example, be used to improve the accuracy of point-particle simulations, enabling better predictions of compressible particle-laden flows.
December 4, 2024 | New peer-reviewed paper published
In our latest paper published in Physics of Fluids, led by Pierre and selected as an Editor's Pick by the editors of the journal, we propose a low-dimensional modelling approach to simulate the dynamics, acoustic emissions, and interactions of cavitation bubbles. With this new model, we're able to show that the finite propagation speed of the acoustic waves has a pronounced influence on the pressure-driven bubble dynamics in dense bubble clusters and the onset of cavitation in response to a change in ambient pressure. The model is now also available open source as part of the software toolbox APECSS.
November 27, 2024 | CSME Fluid Mechanics Symposium
The annual congress of the Canadian Society for Mechanical Engineering (CSME) will be held jointly with the annual conferences of the CFD Society of Canada and of the Canadian Society of Rheology at École de technologie supérieure (ÉTS) in Montréal, 25-28 May 2025. As part of the CSME congress, Fabian is co-organizing the Fluid Mechanics Symposium, which is aimed at showcasing the latest research in fluid mechanics from researchers in Canada and abroad. The submissions deadline for abstracts/papers is 31 January 2025.
October 22, 2024 | New peer-reviewed paper published
In this paper published in the Journal of Computational Physics, we introduce a fully coupled algorithm for interfacial flow simulations with implicit surface tension treatment. This approach, applicable to flows with large density and viscosity ratios, demonstrates energy conservation and efficiency in resolving surface-tension-driven phenomena, including the Laplace equilibrium and Rayleigh-Plateau instability, even with time steps exceeding the traditional time-step constraints associated with surface tension.
August 8, 2024 | New peer-reviewed paper published
In this paper published in the International Journal of Multiphase Flow, we study the dispersion of particles in evaporating sessile droplets on heated substrates, using fully resolved CFD simulations in which the particles are modelled using a discrete element method (DEM). Our study shows that thermocapillary Marangoni stresses significantly enhance fluid motion and convective mixing within a droplet, with velocities nearly two orders of magnitude larger than those from capillary flow due to evaporation. These stresses dominate particle dispersion by reducing the influence of evaporation-driven interface motion and gravity-induced sedimentation, driving particles first toward the droplet apex and then toward a stagnation point on the interface.
July 6, 2024 | INI program on multiphase flows
For the next 12 days, Fabian is participating in the research program "The mathematics of multiphase flows with applications" of the Isaac Newton Institute for Mathematical Sciences, held this month at the University of East Anglia in Norwich (UK). As part of a co-currently running workshop "New directions in multiphase flows", Fabian will give an invited seminar on our work related to accelerating interfacial flow simulations by breaching the capillary-time step constraint.
June 26, 2024 | ICNMMF-5
This week, Fabian is attending the 5th International Conference on Numerical Methods in Multiphase Flows in Reykjavik (Iceland), the foremost international conference on multiphase flow modelling. The conference program includes two contributions related front-tracking methods from us and our collaborators.
June 20, 2024 | New peer-reviewed paper published
In this paper published in Langmuir, a leading journal on interface science published by the Americal Chemical Society, we present a numerical algorithm for evaporation sessilse droplets based on a lubrication approximation, which considers both pinned and moving contact lines. Using this new algorithm, we present a detailed study of the dispersion and deposition of particles in evaporating sessile droplets in fuction of the contact angle, the contact line motion, thermocapillarity, evaporation rate and deposition rate. While particles are preferentially deposited near the contact line when the evaporation rate is high, leading to a so-called coffee ring, thermocapillarity and fast contact line motion is found to favour the deposition of particles near the center of the droplet. This work is the results of a fruitful collaboration with Luca Biancofiore and his group.
May 26, 2024 | CSME Congress 2024
The annual congress of the Canadian Society for Mechanical Engineering (CSME) currently takes place in Toronto. Fabian is participating in the congress as one of the organizers of the Fluid Mechanics Symposium as well as a presenter, showcasing our work on steering jetting cavitation.
May 19, 2024 | ILASS-Americas 2024
Fabian is at Cornell University in Ithaca, NY (USA) for the 34th Annual Conference on Liquid Atomization and Spray Systems, North and South America, where he is giving one of three invited keynote lectures. His keynote focuses on our research into breaching the capillary time-step constraint and accelerating interfacial flow simulations with surface tension.
May 9, 2024 | New peer-reviewed paper published
In this new review paper, published in the journal Physics of Fluids and selected by the journal's editorial board as a Feature Article, Fabian reviews the Kirkwood-Bethe hypothesis, which was originally proposed in 1942 as a means to close the equations that govern pressure-driven bubble dynamics as well as the resulting flow field and acoustic emissions in spherical symmetry. This review puts the Kirkwood–Bethe hypothesis on a complete theoretical foundation, gathers and summarizes contemporary models derived from it, and proposes a generalization of the Kirkwood–Bethe hypothesis to arbitrary single-dimensional domains and a method to treat shock waves.
February 5, 2024 | New peer-reviewed paper published
In this study, published today in the Journal of Acoustical Society of America, the propagation of acoustic waves in non-uniform flows is investigated by incorporating a leading-order model of acoustic pressure modulation into a Lagrangian wave tracking algorithm. Using this numerical method, we demonstrate that non-uniform flows modulate of the pressure amplitude of acoustic waves propagating in it. This suggests that spatial velocity gradients drive acoustic pressure modulations in any non-uniform flow, which can, as shown here, be readily quantified.
January 13, 2024 | CACSE Conference 2024
Fabian is currently in Banff, Alberta (Canada) to participate in the 2nd Conference of the Canadian Association for Computational Science and Engineering, where he will present our work on developing a fully coupled numerical framework viscoelastic interfacial flows.
January 11, 2024 | New peer-reviewed paper published
In our new paper, published in the Journal of Fluid Mechanics, we present a collaborative study with the group of Claus-Dieter Ohl in which we investigate, experimentally and numerically, how jetting cavitation collapse changes when subjected to a stagnation flow, i.e. a flow that impinges perpendicular onto a solid wall. High-speed imaging shows rich and rather distinct bubble dynamics for different wall jet flow velocities and bubble-to-wall stand-off distances. The simulations allow us to numerically determine the microscopic and transient pressures and shear stresses on the wall. The shear stresses can be increased by orders of magnitude without increasing impact pressures the same way. Interestingly, at small seeding stand-offs, the bubble during the final collapse stage can lift off the wall and migrate against the flow direction of the wall jet such that the violent collapse occurs away from the wall.
