Upcoming Events

07

2025.04

The 1st International Symposium on Non-equilibrium Transport Phenomena
28

2024.11

Recent advances of numerical modelling of coastal engineering problems: breaking waves and sediment transport

This talk will focus on challenges and recent research breakthroughs on computational fluid dynamics (CFD) modelling of related coastal engineering problems in terms of (1) breaking waves in the coastal surf zone and (2) sediment transport/ scour with considering the seepage in the porous soil. For CFD modelling of coastal processes, breaking waves and sediment transport are the most challenging problems, as well as their interaction with coastal structures. Our recent works with Reynolds stress turbulence models (RSM), yielded unprecedented accuracy in the prediction of coastal breaking waves on a sloped beach, as well as breaking wave-structure interaction. For sediment transport problems, our recent study has coupled the hydrodynamic and morphological processes with the dynamic seepage effect in the seabed, and for the first time achieved full scale simulations of tsunami-induced sediment transport and scour.
19

2024.11

Modeling of reservoir applications relevant to CO2 sequestration portfolio

Subsurface reservoirs are used for various applications driving the energy transition towards zero-carbon energy. Making optimal use of subsurface reservoirs is a great challenge for society these days. CO2 capture, utilization and sequestration (CCUS) can play a significant role in reducing anthropogenic CO2 emissions while allowing society to slowly phase out traditional energy sources. An accurate representation of CCUS requires computationally expensive modelling of complex physical phenomena at various scales. These models involve many uncertain reservoir parameters and imprecise input information, demanding the generation of representative ensembles of models thus making the computational cost even higher. In this talk, I will share our experience in the simulation of CCUS applications using high fidelity physics-based computational models. I will present the parametrization technology which allows us to develop a unified modelling framework with multiphase thermal-compositional formulation capable to cover a wide variety of CCUS challenges. Several reservoir engineering applications relevant to CO2 sequestration portfolio will be shown as well.
19

2024.11

Accelerating energy transition with high-performance computing of multi- phase, reacting thermo-fluid systems
08

2024.11

All defects are equal, but some are more equal than others: A disordered story

Topological defects play a fundamental role in modern physics from cosmic strings in the universe to vortices in superfluid. Topological defects, such as dislocations, are also essential to describe mechanical failure and plastic flow in crystalline materials. Amorphous solids (e.g., glasses), lacking an ordered lattice structure, are ubiquitous in nature and they also exhibit plastic behavior and soft spots -- regions more prone to local rearrangements. Nevertheless, a microscopic theory of these phenomena is still lacking because of the difficulty of defining defects in an already disordered environment. In this talk, I will review recent developments claiming that topological defects can be still defined in disordered solids in the space of vibrational modes or in the dynamical displacement field. I will show how these defects can be correlated to soft spots and used to predict the plastic behavior in 2D and 3D glasses. Finally, by taking a step back and considering defective crystals, I will show how these newly proposed dynamical defects relate to well-established structural defects. I will comment on open questions and connections to other theories of defects in glasses.
05

2024.11

Paradoxes of Severe Plastic Deformation: Scientific Foundations and Innovative Applications

Recent studies in processing of metallic materials by severe plastic deformation (SPD) techniques clearly showed that target nanostructuring can result in their paradoxial properties that usually are not typical for the materials subjected to conventional thermomechanical treatment. Such paradoxes constitute the combinations of high strength and ductility, demonstration of high strength and electrical conductivity, increased corrosion resistance and other. Herein, unusual combinations of mcchanical and functional propcrtics arc rcported following rcccnt rcsults and findings on a number of metallic materials processed by SPD as well as the physical mechanisms that are key to their origin associated with various nanostructured features from grain refinement to nanoscale and phase transformation. High innovation potential for application of these multifunctional materials in enginccring and medicine is considered and discussed.
05

2024.11

Osseointegration of nanoTi and nanoMg implants

High-strength commercially pure nanostructured Ti Grade 4 (nanotitanium) is very promising for manufacturing medical implants with improved design. In this work the osseointegration properties of nanostructured (NS) and initial coarse-grained (CG) Ti Grade 4 with different surface treatments were studied: 1 - NS after mechanical polishing: 2 - NS after mechanical polishing and subsequent chemical etching; 3 - CG after mechanical polishing; 4 - CG after polishing and etching. Chemical etching of the samples was performed in ammonia piranha solution with an exposure time of 2 hours. Roughness parameters were measured for each sample type using an NT-MDT Integra Prima scanning probe microscope.
22

2024.10

A new theory and practices for composite laminates

Traditional quad with fixed 0, ±45 and 90 plies can be replaced by double-double (DD in [±Φ /±Y]) that offers natural mid-plane symmetry,easy homogenization, tapered components, single ply drops, scaling design without recalculation, and layup of pre-plied tapes or sheets. Complications from Quad in anisotropic flexural rigidity, thousand stacking sequences, and inability to interpolate or taper will alldisappear with DD. Trace and the area offailure envelopes can be the single parameters to rate materials and laminates, respectively. Ifmaterial A is 20 stiffer or stronger than material B, that ratio applies to all laminates; when laminate A is 30 percent over laminate B, that ratio applies to all materials. Stress concentration factors, search for strongest laminates, and measuring compressive and shear strengths are all simpler because they do not change with materials. Laminate selection is the key. Field-based DDis rational and flexible that discrete Quad cannot match, and will make composites more competitive.
16

2024.10

Hydrodynamic Simulations of Microswimmers

In this talk I will describe our recent simulations efforts to understand the collective motion of small micrometer sized active particles suspended in a liquid environment. Specifically, I will concentrate on the effects of chirality in these systems. This concerns two specific examples. In the first part, we study collective motion in bulk suspensions of spherical microswimmers with chiral trajectories. Using a generic model, we demonstrate that both circular and helical swimmers can synchronise their rotation. In the second part, we study achiral swimmers in 3-dimensional nematic liquid crystals. We observe a spontaneous chiral symmetry breaking, where the initially uniform nematic state is kneaded into a continuously twisting state akin to cholesteric liquid crystal. This transition has a hydrodynamic origin and corresponds to a twist-bend instability of the nematic order. Finally, I will present a few results concerning cargo transport using nematic disclinations.
23

2024.08

Vortex Dynamics in The Wake

Wakes form behind any solid object immersed in a fluid that is moving at an appreciable speed. Although viscous,dissipative forces at the fluid-solid interface are largely responsible for the pro- duction of a wake,it is often possible to model the wake itself using the techniques of inviscid fluid dy- namics when the Reynolds number is moderately large.This technique was first used by Theodore von Karman in a series of papers in 1911 that modeled the wake behind a bluff body as a double row of alter- nately-signed point vortices,yielding a formula for the drag force on the object as a function of the vortex street characteristics.In this talk,we will explore how vortex dynamics in an ideal fluid can illumi- nate our understanding of wakes and provide useful quantitative predictions.We will first present a gen- eralization of von Karman's drag law for periodic vortex-street wakes with N vortices per period in a two-dimensional wake.We will then consider periodic arrays of axisymmetric thin-cored vortex rings as a model for three-dimensional wakes.Lastly,we will present a novel numerical method to model the wake behind a flexible swimmer,improving upon the method of Silas Alben (2009,J.Comp.Physics).We will apply this method to a simple model of carangiform swimming.

1