Depth-averaged Lattice Boltzmann and Finite Element methods for single-phase flows in fractures with obstacles

Prediction of the interpass temperature of a wire arc additive manufactured wall: FEM simulations and artificial neural network

This paper presents the results of finite element method (FEM) simulations of heat-transfer and fluid flow of microchannels. These FEM simulations are used in an actuator placement problem for a microchannel network configuration and in formulating an off line control law with the additional use of proper orthogonal decomposition (POD). In the first part of this paper with the use of FEM simulations we investigate the thermal behavior of different materials in microscale. We propose an actuator placement design that is well suited for microchemical systems. This actuator design coupled with a control action allows variations in the temperature profiles within millimeters. In the second part, we propose a control scheme that is based on a POD of the temperature profiles obtained by FEM simulations. This control scheme uses the optimal eigenfunctions obtained from the POD procedure in a minimization procedure that results in the appropriate change in the manipulated input variables.

Investigation of CO2 and CH4 capture from syngas in adsorption process and breakthrough modeling by modified Lattice-Boltzmann mesoscale method

Tempered fractional calculus, as an extension of fractional calculus, has been successfully applied in numerous scientific and engineering fields. Although several traditional numerical methods have been improved for solving a variety of tempered fractional partial differential equations, solving these equations by the lattice Boltzmann (LB) method is an unresolved issue. This paper is dedicated to presenting a novel LB method for the tempered time-fractional diffusion equation. The tempered time-fractional diffusion equation is first transformed into an integer-order partial differential equation by approximating the tempered fractional derivative term. Then the LB method is proposed to solve the transformed objective equation. The Chapman-Enskog procedure is conducted to confirm that the present LB method can accurately recover the objective equation. Some numerical examples with an analytical solution are employed to validate the present LB method, and a strong consistency is observed between the numerical and analytical solutions. The numerical simulations indicate that the LB method is a second-order accurate scheme. The proposed LB method presents a new approach to solving the tempered time-fractional diffusion equation, which is beneficial for the widespread application of the tempered time-fractional diffusion equation in addressing complex transport problems.

This study establishes the forming limit diagram (FLD) for QSTE340 seamed tube hydroforming by finite element method (FEM) simulation. FLD is commonly obtained from experiment, theoretical calculation and FEM simulation. But for tube hydroforming, both of the experimental and theoretical means are restricted in the application due to the equipment costs and the lack of authoritative theoretical knowledge. In this paper, a novel approach of predicting forming limit using thickness gradient criterion (TGC) is presented for seamed tube hydroforming. Firstly, tube bulge tests and uniaxial tensile tests are performed to obtain the stress‐strain curve for tube three parts. Then one FE model for a classical tube free hydroforming and another FE model for a novel experimental apparatus by applying the lateral compression force and the internal pressure are constructed. After that, the forming limit strain is calculated based on TGC in the FEM simulation. Good agreement between the simulation and experimental results is indicated. By combining the TGC and FEM, an alternative way of predicting forming limit with enough accuracy and convenience is provided.

The integration of Finite Element Method (FEM) simulations with laser-based techniques has significantly advanced acoustic research by enhancing wave measurement, analysis, and prediction in complex solid media. This review examines the role of the FEM in laser-based acoustics for wave propagation, defect detection, biomedical diagnostics, and engineering applications. FEM models simulate ultrasonic wave generation and propagation in single-layer and multilayered structures, while laser-based experimental techniques provide high-resolution validation, improving modeling accuracy. The synergy between laser-generated ultrasonic waves and FEM simulations enhances defect detection and material integrity assessment, making them invaluable for non-destructive evaluation. In biomedical applications, the FEM aids in tissue characterization and disease detection, while in engineering, its integration with laser-based methods contributes to noise reduction and vibration control. Furthermore, this review provides a comprehensive synthesis of FEM simulations and experimental validation while also highlighting the emerging role of artificial intelligence and machine learning in optimizing FEM models and improving computational efficiency, which has not been addressed in previous studies. Key advancements, challenges, and future research directions in laser-based acoustic applications are discussed.

Numerical simulation of the temperature distortions in InGaP/GaAs/Ge solar cells working under high concentrating conditions due to voids presence in the solder joint

A lattice Boltzmann method for axisymmetric multicomponent flows with high viscosity ratio

Numerical 3-D FEM simulation of tensor model for liquid crystal displays

With the rapid economic and social development in China, using the full-face rock tunnel boring machine (TBM) in construction is becoming increasingly common. As the principal tool for rock breaking, the efficiency and service life of disk cutters used by the TBM will affect project progress and cost. The failure mechanism of disk cutters is still unclear. The specific impact of the changing temperature during rock breaking on tool failure behavior remains unclear. Therefore, this paper studies the temperature characteristics of disk cutters using the theoretical solution and finite element method (FEM) simulation. The finite difference method discretized the heat conduction equation and boundary conditions. The temperature distribution and variation are solved using coding in MATLAB. FEM simulation using ABAQUS is established to characterize the heat transfer process and analyze the temperature field. Several experiments are conducted for verification. The simulated results correlate well with analytical ones, proving the correctness and accuracy of the proposed method.

Lattice Boltzmann method (LBM) has been applied to predict flow properties of porous media including intrinsic permeability, where it is implicitly assumed that the LBM is equivalent to the incompressible (or near incompressible) Navier-Stokes equation. However, in LBM simulations, high-order moments, which are completely neglected in the Navier-Stokes equation, are still available through particle distribution functions. To ensure that the LBM simulation is correctly working at the Navier-Stokes hydrodynamic level, the high-order moments have to be negligible. This requires that the Knudsen number (Kn) is small so that rarefaction effect can be ignored. In our study, we elaborate this issue in LBM modeling of porous media flows, which is particularly important for gas flows in ultra-tight media. The influence of Reynolds number (Re) on the intrinsic permeability is also discussed.

CBR testing, developed before the Second World War, is still the most commonly used experimental procedure for pavement design. Today, CBR tests are correlated with the resilient modulus, which is a key parameter in current mechanistic pavement design methods. However, results of these correlations have been scattered, indicating that other variables are ignored. The purpose of this study is to show how the value of the CBR test is a function of other variables such as particle size and shape, crushing, and the elastic behaviour of the material. These variables were evaluated through FEM (Finite Element Method) simulations while varying several geotechnical parameters known in practical geotechnics. These FEMs include a linear elastic model and a failure criterion (elastoplastic model) and were prepared for granular soils under drained conditions. The evaluations show that the CBR not only depends on Young’s modulus (the parameter commonly used to correlate with the CBR), but also appears to depend on compressibility due to particle crushing. This appears to be a predominant parameter that can affect the CBR in the elastic domain as much as Young’s modulus does. Finally, this paper provides insights that improve the understanding of variables leading to high or low CBR values for granular materials. In addition, FEM simulations have been compared to the AASHTO Mechanistic-Empirical Pavement Design Guide (MEPDG) and other methodologies used in road geotechnics.

High-G accelerometers have a variety of applications with severe shock loadings especially in crash and impact environments. The package for a high-G accelerometer should provide both protection against such harsh environments and necessary communications with outside the package. The residual stress caused by packaging process which degrades the sensor performance should be considered at the beginning of packaging design. The accelerometer in this study is based on a piezoresistive structure fabricated by a standard MEMS fabrication process. A glass cap was anodically bonded to the structure to protect the movable parts. Then a packaging substrate was fixed to above structures with an adhesive material. FEM simulation based on a simplified structure of the accelerometer has been applied in static analyses in order to find out the potential stress brought by the package. The affection of different adhesive and packaging materials on the accelerometer performance was simulated. The results of simulations show that both the Young's modulus of the adhesive and the coefficient of thermal expansion (CTE) of packaging substrate could have a significant impact on the initial output of the accelerometer. An experiment study on the affection was also conducted, and the results were similar to the results of FEM (finite element method) simulations for the simplified structure. Thus, the FEM simulation of such simplified structure could serve as the basic of accelerometer packaging design. Based on former results, optimized process was suggested in the package of the accelerometer and the packaged accelerometer was tested with satisfactory results

An interaction potential based lattice Boltzmann method with adaptive mesh refinement (AMR) for two-phase flow simulation

An accurate coil design is a fundamental task to maximize signal‐to‐noise ratio in magnetic resonance applications. Coil design techniques take advantage of computer simulations especially when coil size is comparable to the radiofrequency (RF) wavelength. In particular, the estimation of the losses within the conductors as well as the radiative losses, both as a function of frequency, is instrumental to a complete coil performance characterization. However, the cross‐sectional shape of the conductors strongly affects the radiofrequency coil's performance, especially at those frequencies where conductor losses represent the dominant power dissipation mechanism. Indeed, at radiofrequencies, the current flowing in the conductor is distributed in the proximity of its surface instead of being uniformly distributed over the cross section; it follows that an accurate conductor losses estimation can be performed only in the case of wire conductors by using analytical formulations. For strip conductors, although different theoretical approaches have been proposed in literature by taking into account the losses, no closed‐form expression for conductors resistance is available which takes into account both classical and lateral skin effects. In this work, finite element method (FEM) simulations have been performed for estimating conductor and radiative losses in planar surface loops made of strips and circular wires; the results have been compared against analytical formulations and literature data. Workbench tests performed on two circular coil prototypes, the first one constituted by a strip and the second one by circular wire conductors, tuned at 63.9 MHz and 127.8 MHz, showed a good agreement with FEM simulations.