Wei Ge

• PhD
• Professor (Full) at Institute of Process Engineering, Chinese Academy of Sciences

This paper investigates an experimental granular impingement flow system through simulations and energy consumption statistics. With the increase of solid concentration, flow patterns undergo cross flow (dense edge and dilute center), dispersed flow, and mixed-jet flow (dilute edge and dense center) in turn. The influence of gas phase on the flow p...

A new oscillating catalytic reaction is discovered: steam reforming of CH 4 in the presence of SO 2 over Rh nanoparticles. The reducing products from reforming convert SO 2 into adsorbed sulfur, which deactivates the catalyst. Theoretical calculations show how sulfur adsorption causes a subtle shift in the atoms at the stepped edge of the nanoparti...

Direct energy budget is carried out for both cold and hot flow in gas–solid fluidization systems. First, the energy paths are proposed from thermodynamic viewpoints. Energy consumption means total power input to the specific system, and it can be decomposed into energy retention and energy dissipation. Energy retention is the variation of accumulat...

Modeling and simulation of granular materials have received great attention in a wide range of scientific and engineering fields. With various discrete or continuum-based methods facing different aspects of the complexity of granular materials, their multi-scale coupling may lead to more effective and efficient methods. In this work, a novel spatia...

Hollow multi‐shelled structures (HoMS), a new family of hierarchical nano/micro‐structured materials, have evoked intensive studies to discover their unique temporal‐spatial ordering features. The theoretical understanding of the general synthetic methods of HoMS, i.e. the sequential templating approach (STA), makes it possible to understand, predi...

Hollow multi‐shelled structures (HoMS), a new family of hierarchical nano/micro‐structured materials, have evoked intensive studies to discover their unique temporal‐spatial ordering features. The theoretical understanding of the general synthetic methods of HoMS, i.e. the sequential templating approach (STA), makes it possible to understand, predi...

Clusters play a critical role in the hydrodynamics of gas-solid flow. In this work, the probe method, the DBSCAN-based method and the Vorono{\"i}-based method are used to identify clusters in gas-solid suspensions, and their structural and dynamic properties are then quantified. The structural properties obtained by the probe method, including clus...

The Lennard-Jones (LJ) potential function is widely employed in molecular dynamics simulations. In this study, the LJ potentials under different characteristic diameter σ and characteristic energy ε were simulated, and the changes in properties such as number density, total energy, phase transition latent heat, and phase transition temperature were...

Multi-scale porous structures inside and/or between the catalyst pellets or particles are found in many chemical processes, where strong coupling of reaction and transport results in complex apparent reaction kinetics influential to the reactor performance. Traditional continuum-based porous media models and simulation methods can hardly describe s...

In the century-long development of fluidization technology, simulation methods have evolved in response to scientific and engineering demands, which in turn have produced advances in technology. Faced with the profound global challenges of climate change and sustainable development, fluidization has found new applications in carbon capture and util...

The significant self-heating effect severely restricts the performance and reliability of nano-electronic devices. Accordingly, it is very important to understand the process and mechanism of nano/microscale heat transfer for thermal management and thermal design of devices. In this work, we propose a new Lattice Boltzmann Method (LBM) scheme with...

The coarse-grained discrete particle model (DPM) is fast growing into a powerful tool and a useful counterpart of the widely used two-fluid model (TFM) in simulation of large-scale reactors. This work aims to study the role of mesoscale modeling in both TFM and DPM approaches to understand the advantage and disadvantage of each approach for further...

Coarse-grained discrete particle models (CGDPMs) that treat a group of real particles as a coarse-grained particle (CGP) are potentially capable of simulating industrial-scale gas-solid systems. However, the use of large CGPs decreases the spatial resolution for fluid computation, such that the detailed hydrodynamics of mesoscale structures cannot...

Large-scale atomistic simulation of low-dimensional silicon nanostructures has been implemented on a heterogeneous supercomputer equipped with a large number of GPU-like accelerators (GLA). In the simulation, an innovative parallel algorithm was developed for the combined utilization of the dynamic neighbor and static neighbor list algorithms aimin...

The coupling of reaction and diffusion between neighboring active sites in the catalyst pore leads to the spatiotemporal fluctuation in component concentration, which is very important to catalyst performance and hence its optimal design. Molecular dynamics simulation with hard-sphere and pseudo-particle modeling has previously revealed the non-sto...

Granular flow in hoppers is widely encountered in industries and daily life. Despite its ubiquity, understanding on its basic flow behavior is still limited. Typically, the flow may be interrupted by the formation of arches and the phase transition ensues, and in general these arches may not collapse without external energy input such as vibration....

The high-temperature gas effect is critical to the design of high-speed aircraft in terms of the thermal protection at their surfaces. However, studies on this topic are challenging for both experiments and numerical simulation. To cope with the breakdown of continuum methods and the extremely high cost of molecular methods, a multiscale model and...

The adsorption of protein molecules to oil/water (O/W) interface is of critical importance for the product design in a wide range of technologies and industries such as biotechnology, food industry and pharmaceutical industry. In this work, with ovalbumin (OVA) as the model protein, the adsorption conformations at the O/W interface and the adsorpti...

Particle scale information of commercial fluidized beds is important for its design and optimization, e.g., the catalyst performance evolution along time. However, it is difficult to be obtained by in-situ measurements or continuum-based numerical simulations due to the limited accuracy in space and time. Thus, the newly developed reaction model fo...

Euler-Lagrange method is powerful for studying dense gas-solid flow, where the Eulerian grid is typically 3–5 times of particle diameter to ensure the accuracy of information mapping between gas and solid phases. This condition limits its applications in simulating reactors with complex geometries that require the use of Eulerian grids that are com...

A highly efficient and novel atomistic simulation framework is first established for the thermal and mechanical behaviors of a whole microprocessor chip or its constituent functional modules, important for the performance and reliability of high-end microprocessor circuits. Taking the simulation of the thermal behavior as a model system, we first r...

Most natural resources are processed as particle-fluid multiphase systems in chemical, mineral and material industries, therefore, discrete particle methods (DPM) are a reasonable choice of simulation method for engineering the relevant processes and equipment. However, direct application of this method is challenged by the complex multiscale behav...

As a classical example of granular flow, gravity-driven hopper flow has been studied for decades, but an in-depth understanding of its fluctuation is still lacking, especially at small-scale and short-term. In this experimental and numerical study, the time interval (tΔ) between the discharging of two consecutive grains from hoppers under a series...

The nonequilibrium properties and strong spatiotemporal long-range correlations in gas-solid suspensions were analyzed systematically by discrete particle simulation in periodic domains. The effective interphase slip velocity is found to be significantly larger than the particle terminal velocity, the particle velocity distribution function is non-...

It is well accepted that the drag coefficients of incompressible flows past a sphere only depend on the Reynolds number Re. However, the influence of the Mach number Ma on the drag coefficient becomes increasingly obvious for flows with higher Mach numbers. Unfortunately, this influence has not yet been well understood. In this work, a numerical me...

Coal beneficiation via the air dense medium fluidized bed (ADMFB) has increased its popularity in recent decades. However, due to the coexistence of bubbles and the emulsion phases, obtaining a uniform and stable bed density for coal separation in ADMFB remains challenging. In this work, a coarse-grained CFD-DEM method with high accuracy in capturi...

The heat transfer in fluid flow through static assemblies of randomly distributed spheroids, including spheres, prolates, and oblates, is investigated using direct numerical simulation (DNS). Constant heat fluxes are imposed at individual particle surface by the Neumann boundary condition for temperature. The superficial Reynolds number (Re) and th...

Using multi-GPU in lattice Boltzmann method (LBM), fully developed turbulent flow in a square duct at the friction Reynolds numbers ( Re τ ) of 300, 600, 1200 and 1800 are simulated. Through simulation of three-dimensional lid-driven cavity flow under different Reynolds number ( Re ), the accuracy of lattice Bhatnager-Gross-Krook (LBGK) multi-GPU p...

Particle-resolved direct numerical simulation of a 4-baffled cylindrical stirred tank with a 6-pitched blade-turbine-downflow (PBTD) impeller was carried out for the first time to understand the hydrodynamic characteristics of its turbulent solid-liquid flow. The fluid-particle and fluid-wall interactions are numerically described by the immersed b...

A computational fluid dynamics-discrete element-immersed boundary method (CFD-DEM-IBM method) was developed for Cartesian grid simulation of the hydrodynamics and heat transfer of compressible gas–solid flow, where the interaction of gas and complex geometries was modeled using the IBM. The IBM was first validated by simulating single-phase flow pa...

Discrete particle method (DPM) and direct numerical simulation (DNS) have been widely used to simulate gas-solid flow. DPM is computationally efficient but its accuracy is significantly dependent on the selection of interphase interaction models, whereas DNS is accurate but computationally expensive. In this work, we proposed a multi-scale method,...

Hydrodynamic features of gas-solid generalized fluidization can be well expressed in the form of phase diagrams, which are important for engineering design. Mesoscale structure presents almost universally in generalized fluidization and should be considered in such phase diagrams. However, current phase diagrams were mainly proposed for cocurrent u...

Direct numerical simulation on the turbulent flow between two parallel walls under constant heat flux reveals that, adding neutrally buoyant finite-size particles at volume fractions of 0.1 and 0.3 and bulk particle Reynolds numbers of 3800 and 5600 in general reduces the Nusselt number on average but enhances it near the walls. The enhancement is...

Long-time behaviors widely exist in gas–solid reactors, e.g., the coke deposition and catalyst deactivation in the methanol to olefins (MTO) process. Due to the limitation of the computational cost, previous simulations of MTO reactors were mainly conducted with two-fluid model at short-time scales and assumed that the catalyst are perfectly mixed....

The energy-minimization multi-scale (EMMS) model has succeeded in describing the mesoscale structures in gas-solid fluidization by introducing a stability condition to complete the model, viz., the mass specific energy consumption for suspending and transporting the solids, Nst tends to be a minimum. However, direct verification of this condition i...

Coal beneficiation technology using gas-solid fluidized bed is a hot topic in recent decade, however its proper design and scale-up remain a great challenge due to the very complex gas-solid flow involved. To this end, an Eulerian-Lagrangian-Lagrangian (ELL) model (Zhang et al., Renewable Energy, 2019, 136:193-201) was used to intensify the coal be...

The use of CFD-DEM method to accurately simulate gas-solid flows in complex geometries is challenging, mainly due to the complexity related to the use of unstructured computational grids. In order to solve this problem, researchers have simulated gas-solid fluidized beds with complex geometries using CFD-DEM-IBM method with Cartesian grids. In pres...

Drag plays a crucial role in hydrodynamic modeling and simulations of gas–solid flows, which is significantly affected by particle Reynolds number, solid volume fraction, heterogeneity, granular temperature, particle‐fluid density ratio, and so on. To clarify and quantify the multiscale effects of these factors, large‐scale particle‐resolved direct...

Based on the molecular dynamics software package CovalentMD 2.0, the fastest molecular dynamics simulation for covalent crystalline silicon with bond-order potentials has been implemented on the third highest performance supercomputer "Sunway TaihuLight" in the world (before June 2019), and already obtained 16.0 Pflops (1015 floating point operatio...

Gas–solid counter-current downer reactors, in which particles move downward in an upward gas flow, can achieve high solid concentration for high heat and/or mass transfer rates. However, the particles may reverse their direction or even be carried out of the reactor as the gas flow rate increases. This is closely related to “flooding” in counter-cu...

A heterogeneous solid stress model based on the energy minimization multiscale (EMMS) model is developed. The EMMS model is used in the multiscale decomposition of a heterogeneous gas–solid system, and the local flow field inside a computational cell can thus be divided into a series of dense phases and a dilute phase with uniform solid distributio...

The discrete element method (DEM) is used to analyze complex practical granular systems; however, the representation of real shapes is an important consideration because behavior of non-spherical particles is unlike that of spherical particles both individually and collectively. In this study, we use non-uniform rational basis-splines (NURBS) to de...

The coexistence of large particles (such as biomass or coal particles) and fine particles in gas-solid flow is common. In this study, an Eulerian-Lagrangian-Lagrangian method (EMMS-DPM-DEM) was developed to simulate the binary gas-solid flow containing particles of significantly different sizes, where fine particles were simulated using coarse grai...

The coupling of reaction and diffusion processes on catalytic surfaces leads to spatio-temporal heterogeneity in concentration. Understanding of this phenomenon is very important for better catalyst design and higher reaction efficiency. In this work, molecular dynamics simulations combing hard-sphere and pseudo-particle modeling are carried out to...

Direct numerical simulation (DNS) of gas–solid flow at high resolution has been carried out by coupling the lattice Boltzmann method (LBM) for gas flow and the discrete element method (DEM) for solid particles. However, the body force periodic boundary condition (FPBC) commonly used to cut down the huge computational cost of such simulation has fac...

This article reviews the general features of the multiscale structures in particle–fluid systems and the characterization, modeling, and simulation methods for these systems. The discussion focuses on the effects of mesoscale behavior, especially those present in process industries for materials and energy transformation and utilization. When there...

Accounting for complex mesoscale structures was found to be the key to predicting system performance from elemental properties, and hence a bottleneck for process systems engineering. The development and generalization of the energy-minimization multiscale (EMMS) model may present a continuous attempt to provide this key link, where mesoscale struc...

Tapered gas-solid risers have been used in some industrial processes in order to adapt to the requirements of various reactions, but little attention was paid to these reactors in previous investigation. In this work, three-dimensional gas-solid flow in tapered-out and tapered-in risers was simulated by the two-fluid model using an improved structu...

The combination of (quasi‐)real‐time simulation on industrial processes and virtual reality technologies may lead to a new paradigm of research and development in chemical engineering, that is, virtual process engineering (VPE). However, as the main engines of VPE, accurate and efficient simulation methods are still in urgent demand. In this paper,...

Gas–solid two-phase flow is ubiquitous in nature and many engineering fields, such as chemical engineering, energy, and mining. The closure of its hydrodynamic model is difficult owing to the complex multiscale structure of such flow. To address this problem, the energy-minimization multi-scale (EMMS) model introduces a stability condition that pre...

The energy-minimization multiscale (EMMS) principle of compromise in competition is believed to be generally applicable for all mesoscale problems at different levels in the real world, spanning from elementary particles to the universe. This stimulated a fundamental proposition of the concept of mesoscience. This article discusses a potential univ...

This presentation discusses the challenges and opportunities at different levels of process engineering. It is indicated that all processes involve in multilevel structures, each multiscaled, and the complexity of each level exists always at the corresponding mesoscale at the specified level. On the other hand, these mesoscale structures at differe...

The mixing of non-spherical particles is often encountered in various industrial fields, but its mechanism is not well understood. Because of the complexity of contact detection for non-spherical particles, most simulations on particle mixing using the discrete-element method (DEM) are restricted to spherical particles. In this work, an efficient a...

This paper investigates the landscape of extremum characteristics for different energy consumption terms in gas-solid fluidization based on the Energy Minimization Multi-Scale (EMMS) model. The influence of typical cluster correlations on the extremum characteristics is also investigated to consolidate the study results. The energy consumption term...

Searching of the interaction pairs and organization of the interaction processes are important steps in molecular dynamics (MD) algorithms and are critical to the overall efficiency of the simulation. Neighbor lists are widely used for these steps, where thicker skin can reduce the frequency of list updating but is discounted by more computation in...

Most porous media (just like catalyst pellets) have complicated pore structures, and understanding the coupling of the diffusion and reaction processes in these pores is very important for improving their performance. In this work, a diffusion factor (D) and a reaction factor (R) are proposed to quantitatively describe the diffusion and reaction pe...

The energy-minimization multiscale (EMMS) principle of compromise in competition is believed to be generally applicable for all mesoscale problems at different levels in the real world, spanning from elementary particles to the universe. This stimulated a fundamental proposition of the concept of mesoscience. This article discusses a potential univ...

Quantification of multiscale heterogeneity is the key to the simulation of gas-solid two-phase flow. The energy-minimization multiscale (EMMS) model can be used at different scales to describe local and global heterogeneities as well as steady-state fluid dynamics of gas-solid fluidization. However, the same cluster diameter correlation based on en...

Gas–solid riser flows tend to be characterized by particle clusters that significantly affect the flow, the mass/heat transfer, and the reaction behavior. To account for the effect of such particle clustering on the mass transfer between gas and particles, we use a lattice Boltzmann model with coupled mass transfer to conduct fully resolved simulat...

The cohesive solids in liquid flows are featured by the dynamic growth and breakage of agglomerates, and the difficulties in the development, design and optimization of these systems are related to this significant feature. In this paper, discrete particle method is used to simulate a solid–liquid flow system including millions of cohesive particle...

Multiphase chemical reactors with characteristic multiscale structures are intrinsically discrete at the elemental scale. However, due to the lack of multiscale models and the limitation of computational capability, such reactors are traditionally treated as continua through straightforward averaging in engineering simulations or as completely disc...

Continuum methods are not accurate enough for flows at high Knudsen numbers, whereas rigorous molecular dynamics (MD) methods are too costly for simulations at practical dimensions. Hard-sphere (HS) model is a simplified MD method efficient for dilute gaseous flow but is of poor parallelism due to its event-driven nature, which sets a strong limita...

The drag models typically used for gas-solids interaction are mainly developed based on homogeneous systems of flow passing fixed particle assembly. It has been shown that the heterogeneous structures, i.e. clusters and bubbles in fluidized beds, need to be resolved to account for their effect in the numerical simulations. Since the heterogeneity i...

Eulerian-lagrangian simulation of bubbly flow has the advantage of tracking the motion of bubbles in continuous fluid, and hence the position and velocity of each bubble could be accurately acquired. Previous simulation usually used the hard-sphere model for bubble-bubble interactions, assuming that bubbles are rigid spheres and the collisions betw...

In this study, flow regions in flat bottomed cylindrical gravity-driven hoppers are investigated in terms of velocity and voidage distributions of particles via GPU-based DEM (discrete element method) simulation. For the first time, the hopper flow with steady discharge is described as nine regions which are essential and critical for better unders...

Mesoscale phenomena represent a common challenge in chemical engineering. This article reviews three decades of related research at IPE, CAS, spanning from the energy-minimization multiscale (EMMS) model specific for gas–solid fluidization to the EMMS principle, which is probably general for all mesoscale problems. This review focuses on elucidatin...