Nishant Kumar

ORCID: 0000-0003-4867-1543
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About
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Research Areas
  • Granular flow and fluidized beds
  • Geotechnical Engineering and Soil Mechanics
  • Landslides and related hazards
  • Material Dynamics and Properties
  • Railway Engineering and Dynamics
  • Geotechnical Engineering and Underground Structures
  • Brake Systems and Friction Analysis
  • Mechanical stress and fatigue analysis
  • Soil Mechanics and Vehicle Dynamics
  • Civil and Geotechnical Engineering Research
  • Synthesis of Organic Compounds
  • Geotechnical and Geomechanical Engineering
  • Carbohydrate Chemistry and Synthesis
  • Pickering emulsions and particle stabilization
  • earthquake and tectonic studies
  • Theoretical and Computational Physics
  • Rheology and Fluid Dynamics Studies
  • Analytical Chemistry and Chromatography
  • Soil and Unsaturated Flow
  • Adhesion, Friction, and Surface Interactions
  • Magnesium Alloys: Properties and Applications
  • Coagulation and Flocculation Studies
  • Cyclone Separators and Fluid Dynamics
  • Microwave Dielectric Ceramics Synthesis
  • Hydrocarbon exploration and reservoir analysis

Virtual Vehicle (Austria)
2019-2023

Deutsches Zentrum für Luft- und Raumfahrt e. V. (DLR)
2020-2022

University of Twente
2012-2015

Indian Institute of Science Education and Research Kolkata
2010

Indian Institute of Technology Kanpur
2007-2008

Google (United States)
2007

University of Maryland, College Park
1992

In this paper, the ageing behaviour of suspensions laponite with varying salt concentration is investigated using rheological tools. It observed that accompanied by an increase in complex viscosity. The creep experiments performed at various ages show damped oscillations strain. characteristic time scale oscillations, retardation time, shows a prominent decrease increasing age system. However, dependence weakens concentration, which known to change microstructure system from glass like gel...

10.1098/rspa.2007.0250 article EN Proceedings of the Royal Society A Mathematical Physical and Engineering Sciences 2007-12-04

Soft, disordered, micro-structured materials are ubiquitous in nature and industry, different from ordinary fluids or solids, with unusual, interesting static flow properties. The transition fluid to solid -at the so-called jamming density- features a multitude of complex mechanisms, but there is no unified theoretical framework that explains them all. In this study, simple yet quantitative predictive model presented, which allows for variable, changing density, encompassing memory...

10.1007/s10035-016-0624-2 article EN cc-by Granular Matter 2016-07-02

Physical experiments can characterize the elastic response of granular materials in terms macroscopic state variables, namely volume (packing) fraction and stress, while microstructure is not accessible thus neglected. Here, by means numerical simulations, we analyze dense, frictionless assemblies with final goal to relate moduli fabric state, i.e., microstructural averaged contact network features as number density anisotropy. The particle samples are first isotropically compressed then...

10.1007/s00707-014-1155-8 article EN cc-by Acta Mechanica 2014-06-25

Ballasted tracks are the commonly used railway track systems with constant demands for reducing maintenance cost and improved performance. Elastic layers increasingly improving ballasted tracks. In order to better understand effects of elastic layers, physical understanding at ballast particle level is crucial. Here, discrete element method (DEM) investigate - under sleeper pad ( USP ) sleeper/ballast interface mat UBM ballast/bottom on micro-mechanical behavior ballast. DEM model, Conical...

10.1007/s10035-019-0956-9 article EN cc-by Granular Matter 2019-10-24

Stress- and structure-anisotropy (bulk) responses to various deformation modes are studied for dense packings of linearly elastic, frictionless, polydisperse spheres in the (periodic) triaxial box element test configuration. The major goal is formulate a guideline procedure how calibrate theoretical model with discrete particle simulations selected tests then predict another calibrated (parameters).Only simplest possible particulate material chosen as basic reference example all future...

10.14356/kona.2013011 article EN cc-by KONA Powder and Particle Journal 2013-01-01

The dynamic wheel-rail contact forces resulting from the interaction between vehicle and track are responsible for local settlement. If these settlements vary along track, geometric irregularities develop further amplifying loading of caused by track. In this work, an efficient vehicle-track (VTI) model is presented predicting long-term evolution vertical settlement during operation. VTI has two interacting components – describes dynamics 8th a car. considers elastic rail on discrete...

10.1177/09544097211024803 article EN cc-by-nc Proceedings of the Institution of Mechanical Engineers Part F Journal of Rail and Rapid Transit 2021-10-27

This paper presents a whole system model framework that enables holistic prediction of accumulated track damage in railway turnouts. A modular approach allows for insight into the interaction different mechanisms such as rail profile change due to plastic deformation and wear well settlement. The methodology focuses on two most critical areas turnout terms damage: switch crossing panels. It is shown at beginning service life running surface rails these significantly deformation, which turn...

10.1080/00423114.2021.1988116 article EN cc-by-nc-nd Vehicle System Dynamics 2021-10-24

We present numerical evidence for an additional discontinuous transition, upon compression, inside the jammed regime asymmetric bidisperse granular packing. This transition line separates states with networks of predominantly large particles from formed by both and small particles, is indicated a discontinuity in number contributing to network. The emerges curves jamming transitions terminates end point where vanishes. starting at size ratio around $\ensuremath{\delta}=0.22$ grows longer...

10.1103/physrevlett.125.215501 article EN cc-by Physical Review Letters 2020-11-17

The challenge of dealing with cohesive powders during storage, handling and transport are widely known in the process pharmaceutical industries. Simulations discrete element method (DEM) provide further insight into local microstructure bulk materials. In this work, DEM approach is presented to investigate flow behavior granular systems subjected different modes deformations. When uniaxial compression applied frictionless, polydisperse spheres above jamming (transition from fluid-like state...

10.4028/www.scientific.net/amr.508.160 article EN Advanced materials research 2012-04-01

Understanding the mechanical stiffness of closely packed, dense granular systems is interest in many fields, such as soil mechanics, material science and physics. The main difficulty arises due to discreteness disorder materials at microscopic scale which requires a multi-scale approach. Discrete Element Method (DEM) powerful tool inspect influence contact properties its individual constituents on bulk behavior assemblies. In this study, isotropic deformation mode polydisperse packings...

10.1088/1755-1315/26/1/012008 article EN IOP Conference Series Earth and Environmental Science 2015-09-09

We present 3D DEM simulations of bidisperse granular packings to investigate their jamming densities, $\phi_J$, and dimensionless bulk moduli, $K$, as a function the size ratio, $\delta$, concentration small particles, $X_{\mathrm S}$. determine partial total moduli for each packing report transition diagram, i.e., density or volume fraction marking both first second transitions system. At large enough difference, e.g., $\delta \le 0.22$, $X^{*}_{\mathrm S}$ divides diagram with most...

10.1103/physreve.106.054903 article EN Physical review. E 2022-11-16

Physical experiments can characterize the elastic response of granular materials in terms macroscopic state-variables, namely volume (packing) fraction and stress, while microstructure is not accessible thus neglected. Here, by means numerical simulations, we analyze dense, frictionless, assemblies with final goal to relate moduli fabric state, i.e., micro-structural averaged contact network features as number density anisotropy. The particle samples are first isotropically compressed later...

10.48550/arxiv.1506.02992 preprint EN other-oa arXiv (Cornell University) 2015-01-01

We analyze the behavior of a frictionless dense granular packing sheared at constant volume. Goal is to predict evolution effective moduli along loading path. Because structural anisotropy that develops in system, volumetric and deviatoric stresses strains are cross coupled via four distinct quantities, classical bulk shear two moduli. Here, by means numerical simulation, we apply small perturbations various equilibrium states previously experienced different pure investigate effect...

10.1063/1.4812162 article EN AIP conference proceedings 2013-01-01

(III): [4 alpha,6 beta(E)]-(+-)-6-(2-[2-(4-Fluoro-3-methylphenyl)- 4,4,6,6-tetramethyl-1-cyclohexen-1-yl]ethenyl)-4-hydroxytetrahy dro pyran-2-one (RG-12561) dichloromethane solvate, 2C24H31FO3.CH2-Cl2, Mr = 857.94, triclinic, Pl, a 11.7413 (5), b 13.0279 c 16.2332 (9) A, alpha 99.456 (4), beta 94.217 gamma 101.893 (4) degrees, V 2381.9 A3, Z 4 [four molecules of (III)+two solvent per unit cell], Dx 1.195 g cm-3, Cu K alpha, lambda 1.54178 mu 16.69 cm-1, F(000) 912, T 293 K, final R 0.053,...

10.1107/s0108270191010077 article EN Acta Crystallographica Section C Crystal Structure Communications 1992-04-15
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