In the current paper, finite element method is employed for numerical simulations and the study of influential parameters on elastic modulus of polymer-matrix nano-composites. Effects of different key parameters including particle elastic modulus, interphase elastic modulus, matrix elastic modulus, interphase thickness and particle volume fraction on total elastic modulus of nano-composite materials are observed in order to shed some light on experimental parameters that are difficult to measure. To this end, a three phase (i.e. particle, interphase and matrix) unit cell is modelled and results compare with previously introduced theoretical model. It is found that interphase parameters such as elastic modulus and thickness strongly influences the elastic properties of the nano-composite and cannot be neglected.

This paper undertakes a critical examination of Stokes’ law in its final form. The examination and insights of the viscosity principle substantiate grounds to suspect that the controlling dynamics are viscous shear rates across a geometry set by solid boundaries only. The examination sets grounds to conduct an analysis of the dynamics based on the viscosity principle alone and a flow model is derived. Based on the relationship between the pressure gradient and the shear forces as mandated by the viscosity principle the analysis suggests that the pressure gradient surrounding settling particles can be computed, is a single value and expands as required to mobilize a force equal to the driving force. In this context, the pressure gradient arises as a consequence of the contest between body forces in the fluid and the shear forces promoted by shear rates. The flow model suggests that Stokes’ law may be missing important information. An analysis is conducted for the settling velocity of non Spherical particles based on the same dynamics and a mathematical solution is reached. The solution is in good agreement with published measured values and defines the influence of particle shape in settling phenomena

Elbow erosion, defined as wall thinning due to the continuous interactions between solid particles and surface, is a common phenomenon in catalyst addition/withdrawal pipeline systems used in residual oil hydrogenation units. This form of erosion can seriously affect the reliable pipeline operation. The present paper describes the construction of realistic cylindrical catalyst particles using the multi-sphere clump method and computational fluid dynamics/discrete element model simulations to study the erosion of pipe walls under different inlet velocities and particle aspect ratios. An optical shooting experiment is carried out to ensure the accuracy of the calculation method, and the model performance is compared using several existing drag models. The results show that the drag model of Haider & Levenspiel is more accurate than the others in revealing the actual cylindrical particle flow. A higher inlet velocity is observed to increase the kinetic energy of the particles and affect their spatial distribution. Specifically, when the Stokes number is greater than 113. 7, the position of the maximum erosion rate shifts from the elbow’s outer wall to the inner wall. Cumulative contact energy is introduced to quantify two different types of particle-wall contacts. With a growing particle aspect ratio, the proportion of tangential energy gradually increases, which indicates that sliding is the main contact mode. The results presented in this paper provide a reference for engineering erosion calculations.

In this paper, an analytical approach combined with a two-dimensional computational fluid dynamics (CFD) model is pursued to simulate the fluid flow in a monopropellant thruster for satellite propulsion systems. The thruster utilizes hydrogen peroxide (H2O2) as a green propellant at a concentration of 87.5%, with a catalytic bed based on Spherical silver particles. Through a parametric analysis of particle diameter, we aim to optimize the design of a monopropellant thruster capable of generating a thrust of 20N. For this purpose, a program in CFD code in the commercially available ANSYS Fluent software is used to solve the energy, momentum, mass transfer, and species transport equations governing the thruster system. The local thermal non-equilibrium (LTNE) approach is used to describe the heat transfer occurring through both the solid and fluid phases within the catalyst bed. The results demonstrate that particle size significantly affects the thermal behaviour, species mass fraction, and exit velocity. An optimum diameter of 0.65mm exhibits the optimal performance of the monopropellant thruster, ensuring efficient decomposition of H2O2 at 968K and providing the required level of thrust force with a specific impulse of about 120s.

This paper follows previous work regarding the settling velocity of non Spherical particles in creeping motion. In the previous work it was found that the shear stress in the fluid is opposed the mass of the fluid. The challenge of the shear stress by the mass imply a pressure gradient by default, i.e. the transfer of the shear stress to the mass is in the form of a surface stress (Pa/m), perpendicular to the shear stress, controlled by the mechanics of viscosity. The dynamics are triggered by the wall shear of the particle. Examination using measured settling velocities shows that the pressure gradient is a unique value for the fluid properties, so that the computed shear stress equal to the viscosity when the velocity gradient is equal to unit and the velocity is satisfied simultaneously, hence, defining the size of the expansion about the shear stress. We learned that application of the viscosity principle demand simultaneous consideration of the volumetric nature of the pressure gradient and the geometry dependence of the velocity gradient. We here undertake an examination to find how the pressure gradient is controlled by the fluid properties and a solution is reached. The solution is in good agreement with published experimental data. In addition we pursued further improvement of the relationships derived previously with further simplification.

The investigation of the terminal falling velocity of non-Spherical particles is currently one of the most promising topics in sedimentation technology due to its great significance in many separation processes. In this study, the potential of Artificial Neural Networks (ANNs) for the prediction of nonSpherical particles terminal falling velocity through Newtonian and non-Newtonian (power law) liquids was investigated using 361 experimental data. ANNs emerged as the most popular non-linear mathematical models due to their good prediction, simplicity, flexibility and the large capacity which moderate engineering endeavor, and the availability of a large number of training algorithms. The developed ANN model demonstrated the acceptable values for the prediction of terminal falling velocities such as the determination coefficient ( R2), MSE, and MRE which were equal to 0. 9729, 0. 0023, and 21%, respectively. In an investigation on terminal falling velocity and drag coefficient of Spherical and non-Spherical particles, it was found that the terminal falling velocity of non-Spherical particles to Spherical particles was 0. 1.