N.U. Khan

Bio: N.U. Khan is an academic researcher from Kuwait University. The author has contributed to research in topics: Markov chain Monte Carlo & Probabilistic forecasting. The author has an hindex of 1, co-authored 1 publications receiving 34 citations.

DEM‐CFD modeling of particle systems with long‐range electrostatic interactions

Abstract: To investigate dynamic behaviors of monocharged particle systems, a direct truncation (DT) method and a hybrid particle-cell (HPC) method are implemented into the discrete element method coupled with computational fluid dynamics (DEM-CFD) with defined cutoff distances. The DT method only considers electrostatic interactions between particles within the cutoff distance while the HPC method computes electrostatic interactions in the entire computational domain. The deposition process of monocharged particles in a container in air was simulated using the developed DEM-CFD. It was found that using the DT method, the macrostructure, evolution of granular temperature, and radial distribution function of the particle system were sensitive to the specified cutoff distance. In contrast, using the HPC method, these results were independent of the specified cutoff distance, as expected. This implies that, although electrostatic interactions between particles with large separation distances are weak, they should be considered in DEM-CFD for accurate modeling of charged particle systems. © 2015 The Authors AIChE Journal published by Wiley Periodicals, Inc. on behalf of American Institute of Chemical Engineers AIChE J, 61: 1792–1803, 2015

Quantifying the effect of homogeneous and localized damage mechanisms on the damping properties of damaged GFRP and CFRP continuous and woven composite laminates—an FEA approach

Abstract: The work reported in this paper describes the development of a hybrid methodology for evaluating the effect of damage on the damping properties of woven damaged woven and non-woven Glass Fiber Reinforced Plastics (GFRP) and Carbon Fiber Reinforced Plastics (CFRP) laminates. The main damage mechanisms considered are matrix cracking and tow fracture. Furthermore, the effect of highly localized damage mechanisms on damping is analyzed, in the case of woven GFRP and CFRP laminates containing a circular notch. This hybrid methodology is a synergy of laboratory observations and Finite Element Analysis (FEA) that eventually leads to the evaluation of the effect of homogeneously distributed damage to a composite laminates damped response, analysis of the vibration of notched laminates that cannot be provided for by continuum mechanics and the analysis of localized damage mechanisms in woven CFRP laminates and generally systems that do not facilitate visual inspection of damage mechanisms.

Modelling of a Beam with a Breathing Edge Crack and Some Observations for Crack Detection

Abstract: The breathing behaviour of closing cracks has been adequately simulated as a small-displacement, frictionless contact problem. The problem of a beam with an edge crack subjected to harmonic loading has been considered as a plane problem and an attempt is made to solve it by using finite elements employing eight-node plane isoparametric elements. The proposed model allows the crack size and position to be varied. Another physically important problem of a cantilever beam held between two heavy jaws at the top and bottom, which are not equally flushed, is considered. This beam is also excited by a harmonic load at the tip. The contact model and a simple single degree of freedom model are used to solve the problem. Both the above problems (cracked beam and beam in offset jaws) show presence of integral multiples of the forcing frequency in their frequency spectra.An important observation regarding cracked beams and beams with imperfect support is made. If the forcing frequency is such that it coincides or is ...