Xiaodong Chen

Xiaodong Chen
Beijing Institute of Technology | BIT · School of Aerospace Engineering

Ph.D.

About

64
Publications
12,029
Reads
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816
Citations
Additional affiliations
January 2018 - present
Beijing Institute of Technology
Position
  • Professor (Associate)
January 2016 - January 2018
Chinese Academy of Sciences
Position
  • Professor (Associate)
June 2013 - December 2015
Chinese Academy of Sciences
Position
  • Professor (Assistant)

Publications

Publications (64)
Article
A hypothetical core destructive accident (HCDA) has received widespread attention as one of the most serious accidents in sodium-cooled fast reactors. This study combined recent advantages in numerical methods to realize realistic modeling of the complex fluid–structure interactions during HCDAs in a full-scale sodium-cooled fast reactor. The multi...
Article
Full-text available
Droplet-based microfluidics offers unique advantages to create platforms that fabricate functionalized particles with increased accessibility, robustness, and simplicity. Herein we present a three-phase microfluidic device that can control the flow pattern to directly generate either core–shell or hole–shell microparticles. The major benefits of th...
Article
Full-text available
Inertial effect has been extensively used in manipulating both engineered particles and biocolloids in microfluidic platforms. The design of inertial microfluidic devices largely relies on precise prediction of particle migration that is determined by the inertial lift acting on the particle. In spite of being the only means to accurately obtain th...
Article
Full-text available
Direct numerical simulations are performed to investigate the multiscale flow physics of binary droplet collision over a wide range of Weber numbers and impact factors. All possible collision outcomes, including bouncing (both head-on and off-center), coalescence, reflexive separation, and stretching separation, are considered. The theoretical form...
Article
The fuel bundle in a fast breeder reactor (FBR) is wrapped with wires for guiding the flow of liquid metal. Under operation condition with irradiation and high temperature, the wrapped bundle undergoes complex contact so that the flow channel of liquid will be affected. There are mainly four factors involved: radiation swelling, thermal expansion,...
Article
Surface-enhanced Raman scattering (SERS) has proved to be an efficient approach for ultrasensitive detection of highly diluted analytes, and the metal colloid-based SERS platform is one of the most successful technique to perform evaporation-assisted collection and enrichment of highly diluted molecules in hot-spot regions on various substrates. Ho...
Article
Full-text available
Droplet microfluidics involving non-Newtonian fluids is of great importance in both fundamental mechanisms and practical applications. In the present study, breakup dynamics in droplet generation of semi-dilute polymer solutions in a microfluidic flow-focusing device were experimentally investigated. We found that the filament thinning experiences...
Article
Full-text available
This paper presents a combined experimental and numerical investigation designed to improve our understanding of how the shape of moving fluid threads evolves under asymmetrical confinements in both circular and square microchannels. Microfluidic devices with two junctions are designed to control the length of the fluid thread at the first junction...
Article
Full-text available
This paper describes a theoretical and numerical investigation of the impact dynamics and outcomes of a microsized water droplet falling onto an oil layer. The shape of the water droplet floating on the oil layer is predicted theoretically to understand the balancing of the three interfacial tensions. Direct numerical simulations coupled with a thr...
Article
Full-text available
Experiments are carried out to study the breakup of moving fluid threads tightly confined in circular microchannels. A configuration with two flow-focusing channel junctions is used to control lengths and deformations of fluid threads at the first and second junctions, respectively. As fluid threads move and deform simultaneously at the second junc...
Article
Full-text available
Confinements regulate capillary instabilities of fluid threads – CORRIGENDUM - Volume 873 - Xiaodong Chen, Chundong Xue, Guoqing Hu
Article
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Diabetic foot ulcers (DFUs), the most serious complication of diabetes mellitus, can induce high morbidity, the need to amputate lower extremities, and even death. Although many adjunctive strategies have been applied for the treatment of DFUs, the low treatment efficiency, potential side effects, and high cost are still huge challenges. Recently,...
Article
Full-text available
We study the breakup of confined fluid threads at low flow rates to understand instability mechanisms. To determine the critical conditions between the earlier quasi-stable necking stage and the later unstable collapse stage, simulations and experiments are designed to operate at an extremely low flow rate. The critical mean radii at the neck centr...
Article
A novel approach for treating vaporization of liquid droplets with large deformation and high mass transfer rate is developed. The formulation is based on decomposed vaporization mechanisms and accommodates the effects of density and property variations in both the gas and liquid phases. In this model, the mass and energy transfer across the interf...
Article
Since most cancer nanomedicine relies on the enhanced permeability and retention (EPR) effect to eradicate tumors, strategies that are able to promote nanoparticle (NP) delivery and extravasation are presupposed to elevate the EPR effect for more effective cancer therapeutics. However, nanothermotherapeutics still suffers from limited drug delivery...
Article
For the shape memory polymers' (SMPs) applications in demanding, high performance scenarios are usually limited by their poor mechanical performances during shape transformation. In this work, shape memory epoxy composites (SMEPCs) with superior mechanical properties are fabricated by adding various short and continuous carbon fibers (CFs) into nea...
Preprint
We study the breakup of confined fluid threads at low flow rates to understand instability mechanisms. To determine the critical conditions between the earlier quasi-stable necking stage and the later unstable collapse stage, simulations and experiments are designed to operate at an extremely low flow rate. Critical mean radii at neck centres are i...
Article
Full-text available
Impinging-jet injectors are widely used in liquid propulsion applications, since their simple configuration provides reliable and efficient atomization. The flowfield involves a series of complicated spatio-temporal evolutions. Much effort has been directed toward understanding the underlying physics and developing quantitative predictions of impin...
Article
Natural organisms such as cactus spines or trachea cilia have unique directional transport ability, owing to their anisotropic surface structures or asymmetric motion. However, most artificial interfacial materials are incapable of transporting macroscale object underwater. Herein, we report that anisotropic microcilia arrays, composed of cobalt fi...
Article
Full-text available
Superhydrophilic coatings: Nanohairs repel mineral buildup Mineral microcrystals that form inside water pipes and cooling towers can now be repelled using hydrogels with bio-inspired shapes. To prevent buildup of calcium-based kidney stones, the human kidney has renal tubules with thin, hair-like morphologies. Jingxin Meng and Shutao Wang from the...
Article
Inertial migration has emerged as an efficient tool for manipulating both biological and engineered particles that commonly exist with non-spherical shapes in microfluidic devices. There have been numerous studies on the inertial migration of spherical particles, whereas the non-spherical particles are still largely unexplored. Here, we conduct thr...
Article
Full-text available
Radial extracorporeal shock wave therapy (rESWT) has been widely used to treat orthopedic disorders and has shown promising clinical results. However, treatments largely rely on clinicians' personal experiences and arbitrary judgments. In article number 1700797, Xiaodong Chen and co‐workers develop a combined experimental and numerical methodology...
Article
Full-text available
Although radial extracorporeal shock wave therapy (rESWT) has been widely used to treat orthopedic disorders with promising clinical results, rESWT largely relies on clinicians' personal experiences and arbitrary judgments, without knowing relationships between administration doses and effective doses at target sites. In fact, practitioners lack a...
Article
Full-text available
We study the dynamics of a small water droplet colliding with an immiscible large sessile oil droplet in the air. Such a three-phase system forms compound microdroplets with tunable structures, depending on whether the small droplet can penetrate into the large one. A structure of penetrative-engulfing is distinguished from structures which are det...
Article
Microfluidic droplets have emerged as novel platforms for chemical and biological applications. Manipulation of droplets has thus attracted increasing attention. Different from solid particles, deformable droplets cannot be efficiently controlled by inertia-driven approaches. Here, we report a study on the lateral migration of dual droplet trains i...
Article
Full-text available
Compound water-in-oil microdroplets can serve as microreactors in chemical and biological analyses. The inkjet printing is a useful technique to generate compound microdroplets by droplet impact. To understand the underlying physics during the droplet impact, a combined experimental and numerical study is carried out. The effect of spreading condit...
Article
Full-text available
The deformation and interaction of a droplet pair in an electric field decide about the success of droplet coalescence. Electric intensity and initial droplet separation are crucial parameters in this process. In this work, a combined theoretical and numerical analysis is performed to study the electrohydrodynamics of confined droplet pairs in a re...
Article
Viscoelasticity-induced particle migration has recently received increasing attention due to its ability to obtain high-quality focusing over a wide range of flow rates. However, its application is limited to low throughput regime since the particles can defocus as flow rate increases. Using an engineered carrier medium with constant and low viscos...
Article
In recent years, inkjet printing, as a new method to fabricate microdroplet microarrays, is being increasingly applied in the fields of biochemical diagnostics. To further improve the general applicability of inkjet printing technology in fabricating biochemical chips, in this work, we introduce a model to describe the multiple injection procedure...
Article
Full-text available
Recent years have witnessed the rapid development of microfluidic technology and microfluidic devices as a multi-disciplinary research field. Compared to conventional methods, micro°uidic technology enables us to precisely manipulate the small volume of multiphase °uids for chemical analysis, advanced materials synthesis, protein crystalliza- tion,...
Conference Paper
Full-text available
Migration of deformable droplets caused by microfluidic inertial effects 1 GUOQING HU, CHUNDONG XUE, XIAODONG CHEN, LNM, Institute of Mechanics, Chinese Academy of Sciences — The inertial effect is an effective way of focusing and sorting droplets suspended in microchannels. Here we conduct nu-merical simulations and experiments on the droplet moti...
Article
Full-text available
The microfluidic inertial effect is an effective way of focusing and sorting droplets suspended in a carrier fluid in microchannels. To understand the flow dynamics of microscale droplet migration, we conduct numerical simulations on the droplet motion and deformation in a straight microchannel. The results are compared with preliminary experiments...
Article
Full-text available
In this paper, a combined theoretical and numerical analysis is performed to study the internal and external flowfields of a liquid swirl injector. The effect of ambient pressure on the injector dynamics is explored systematically over a range of 1-50 atm. An increase in the ambient pressure increases the liquid film thickness, but decreases the sp...
Conference Paper
Electric fields are widely used to induce the coalescence of water-in-oil emulsion droplets in droplet-based microfluidics. The dipole-dipole interaction amplifies the dielectrophorectic force experienced by two neighboring droplets to drive them toward each other. An ac electric field can act in a cumulative manner to merge the adjacent interfaces...
Article
In numerical simulations of multi-scale, multi-phase flows, grid refinement is required to resolve regions with small scales. A notable example is liquid-jet atomization and subsequent droplet dynamics. It is essential to characterize the detailed flow physics with variable length scales with high fidelity, in order to elucidate the underlying mech...
Article
Full-text available
High-fidelity numerical simulations have been performed to study the formation and fragmentation of liquid sheets formed by two impinging jets using an improved volume-of-fluid (VOF) method augmented with several adaptive mesh refinement (AMR) techniques. An efficient topology-oriented (TO) strategy was further established to optimize the performan...
Conference Paper
Full-text available
The complete sequence of events accompanying the head-on collision of two liquid droplets and subsequent breakup was studied numerically using high-fidelity simulation techniques. The formulation is based on the complete set of conservation equations for both the liquid and surrounding gas phases. Based on a open-source flow solver Gerris(http://gf...
Article
Full-text available
In this video, Ray-tracing data visualization technique was used to obtain realistic and detailed flow motions during droplet collision. The differences of collision outcome between Newtonian and non-Newtonian were compared. Various types of droplet collision were presented, including bouncing, coalescence, and stretching separation. Because of the...
Article
Full-text available
In this fluid dynamics video, Ray-tracing data visualization technique was used to obtain realistic and detailed flow motions during impinging of two liquid jets. Different patterns of sheet and rim configurations were presented to shed light into the underlying physics, including liquid chain, closed rim, open rim, unstable rim and flapping sheet....
Article
High fidelity numerical simulations are performed to study the atomization process of impinging jets over a broad range of operating conditions. An improved volume-of-fluid (VOF) method augmented with adaptive mesh refinement (AMR) is used to simulate the formation and breakup of the liquid sheet formed by two impinging jets. In addition, a thickne...
Article
Droplet collision plays an elementary role in dense spray combustion process. When two droplets approach each other, a gas film forms in between. The pressure generated within the film prevents motion of approaching droplets. This fluid mechanics is fluid film lubrication that occurs when opposing bearing surfaces are completely separated by fluid...
Article
In this paper, deformation and breakup of Newtonian liquid droplets at elevated pressures have been studied. Detailed physics pertaining to four different breakup regimes, oscillatory, bag, multimode and shear breakup modes , has been investigated using an incompressible interface tracking methodology. The accuracy and efficiency of the code was en...
Article
The investigations of the collision outcome and dynamics of mass transfer process of unequal-sized binary droplets collision are preformed computationally and theoretically. All the possible collision outcomes, bouncing, coalescence, reflexive and stretching separation are obtained numerically. The present study focuses on water droplet interaction...
Article
The physical mechanism of impact wave and mixing process in the atomization of impinging jets are computationally investigated. Using an accurate adaptive solver for surface-tension-driven interfacial flows, the simulations are found to agree well with experiment data for both wavelength of impact wave and droplet size distribution. The formation o...
Article
Full-text available
In this fluid dynamics video, results from high fidelity numerical simulations are presented, which have been carried out to study the flow and droplet dynamics of liquid sheets formed by two impinging jets. A three-dimensional Volume-of-Fluid (VOF) method with adaptive mesh refinement (AMR) based on octree meshes [1] is used to simulate the variou...
Article
High fidelity numerical simulations have been performed to study the atomization patterns and breakup characteristics of liquid sheets formed by two impinging jets. A fully three-dimensional Volume-of-Fluid method with adaptive mesh refinement (AMR) based on octree meshes is used to simulate the primary atomization. The oblique collision of two cyl...
Conference Paper
A combined theoretical and numerical analysis was performed to explore the flow characteristics in liquid swirl injectors under a wide range of backpressure. Axial velocity in nozzle, surface wave speed and spray pattern were theoretically studied basing on existing theories. Numerical simulations basing on swirl axi-symmetric model were carried on...
Article
High fidelity numerical simulations have been performed to study the atomization patterns and breakup characteristics of liquid sheets formed by two impinging jets. A fully three-dimensional Volume-of-Fluid method with adaptive mesh refinement (AMR) based on octree-mesh is used to simulate the primary atomization. The start of the art visualization...
Article
The effects of backpressure on spraying cone of liquid swirl injector using in liquid rocket engine were studied by combining theory with numerical simulation. Based on theoretical analysis, numerical simulations were carried out by using a swirl axi-symmetric model to solve N-S equations coupled with VOF equation for interior and exterior flow fie...
Article
In order to show the physical mechanism of stationary wave in liquid swirl injector, the equal relation of surface wave phase speed and mean axial velocity at the nozzle part was analyzed based on existing theories. Numerical simulations of the two phase flow field in liquid swirl injector were carried on by solving the Navier-Stokes equations coup...
Article
The film thicknesses of liquid swirl injector under different backpressures were studied theoretically and numerically. A loss coefficient model including friction effect on liquid/gas interface was established based on classical theory. It shows that the theoretical model is not sufficient to show variations of film thickness under different backp...
Article
The previous design methods are not proper to design plug nozzle contours of solid rocket motor using the compound propellant, for the existence of metallized particle phase. The flow characters of plug are changed in the two-phase flow condition, therefore the particle-phase influence must be considered in the design. The ideal plug contour is det...
Article
Solid-Liquid Rocket Ramjet (SLRR) uses both solid and liquid fuels. It has been interested in for its steady combustion character without using a flame stabilizer. The high-temperature gas jet from solid-propellant gas generator of SLRR can work as duty flame for air/liquid fuel combustion at the same time. To attain high combustion efficiency at d...
Article
The aerodynamic characteristics of a maglev (or magnetic levitation) launch assist vehicle were analyzed and rational design principles for its aerodynamic shape were proposed. The aerodynamic shape configuration for the maglev sled as well as for the support and separation structure was analyzed and the optimal values of design parameters were obt...
Article
Maglev launch assist is viewed as an effective method to reduce the cost of space launch. The primary aerodynamic characteristics of the Maglev launch vehicle and the space vehicle are discussed by analyzing their aerodynamic shapes and testing a scale mode in a standard wind tunnel. After analyzing several popular Maglev systems, we present a no-c...
Article
With the need for a low-cost, safe, reliable, and recoverable vehicle to get to space, magnetic launch assist (Maglifter) represents one possible strategy for achieving the vehicle with high ground take-off velocity. In this article, a permanent magnet guideway-high temperature superconductor (PMG-HTS) interaction magnetic levitation (Maglev) syste...
Article
With the aim of finding a low-cost, safe, and reliable way to reduce costs of space launch, a maglev launch assist vehicle (Maglifter) is proposed. We present a permanent magnet–high temperature superconductor (PM-HTS) interaction maglev system for the Maglifter, which consists of a cryostat with multi-block YBaCuO bulks and a flux-collecting PM gu...
Article
Key technologies in Maglev launch assist for space launch were studied, such as magnetic levitation (Maglev), linear motor acceleration, aerodynamic effect and space vehicle separating technology. By the comparison of several Maglev systems, high temperature superconductor (HTS) electrodynamic suspension (EDS) system was viewed as a suited one for...
Article
Various Maglev launch assist concepts were proposed in the world for the aim to find low-cost, safe, and reliable ways to get to space. Among them, high temperature superconducting (HTS) bulk magnetic levitation platform was considered as a better one for Maglev launch assist because of its inherent stability both in the vertical and lateral direct...