Discrete Particle Modelling

A code development project called Mercury

Mercury is a code for discrete particle simulations. That is, it simulates the motion of particles, or atoms, by applying forces and torques that stem either from external body forces, (e.g. gravity, magnetic fields, etc...) or from particle interaction laws. For granular particles, these are typically contact forces (elastic, plastic, viscous, frictional), while for molecular simulations, forces typically stem from interaction potentials (e.g. Lennard-Jones) ....

More at: Mercury Homepage

Sintering - Modelling pressure-, temperature-, and time-dependent contacts

DFG project Particles in contact (PiKo)

In most realistic situations, where particles come in contact, it can NOT be assumed that the contact properties are independent of pressure, temperature or time. Therefore, this project involves pressure-, temperature-, and time-dependent contact properties and their influence on the macroscopic powder flow behavior. Sintering is chosen as one possible example and starting point, where all these phenomena are relevant.

In realistic processes, a sintering process starts with many separate powder- particles that are, e.g., attracted by electrostatic forces, bound together by capillary forces, or squeezed together by strong pressure. Leaving them alone for long time, diffusion will set in and change the contact properties. At elevated temperatures, the sintering works much faster and from the originally isolated particles, a solid, possibly porous and fragile agglomerate is formed.

The goal of this project is to model the particles in contact, before the particles lose their identity. For this, temperature- and pressure-dependent contact models have to be developed in parallel to contact-measurements (with M Kappl, Mainz). The many-particle simulations will then be adapted to the materials used and experimentally validated (with J Tomas, Magdeburg). As the result of the project, the verified numerical model for the sintering process of many particles will become available. This will then be used for the micro- macro transition in order to obtain better theoretical constitutive relations for a macroscopic description based on the contact-mechanics and -physics.

Computational multi-scale modelling of super-dispersed multiphase flows

Strategic Innovative Project (SIP1) of the Institute of Mechanics, Processes and Control (IMPACT), Univ. of Twente

Developing good numerical models for dry granular flow is of interest in many industrial processes and geophysics. Granular material shows both solid and fluid behavior. Closed continuous models for granular flow only exist for certain cases, while Discrete Particle Models (DPM) are unfeasible for large-scale simulations. Therefore I am working on a DG finite element model for heterogeneous multiscale modelling of polydisperse, nonuniform dry granular flows, which allows both efficient and reliable numerical simulations.

Collaborators: A Thornton, S Luding, O Bokhove

A Posteriori Error Estimates of the DG Method for Hyperbolic Systems

A posteriori error estimates are a useful tool to verify the quality of finite element approximations and to control the error in adaptive meshes. We apply the discontinuous Galerkin method to first-order linear hyperbolic systems in two and three space dimensions. We explicitly write down the leading error term and solve local finite element problems to obtain a posteriori error estimates. We present convergence and numerical results for problems from acoustics and electromagnetism.

Collaborators: Slimane Adjerid

1. Thornton, A.R. and Weinhart, T. and Luding, S. and Bokhove, O. Friction dependence of shallow granular flows from discrete particle simulations EPL, submitted October 2011 Download
2. Thornton, A.R. and Weinhart, T. and Luding, S. and Bokhove, O. Modeling of particle size segregation: Calibration using the discrete particle method Modern Physics letter, submitted October 2011 Download
3. Weinhart, T. and Thornton, A.R. and Luding, S. and Bokhove, O. Closure Relations for Shallow Granular Flows from Particle Simulations. Granular Matter, submitted August 2011. Download
4. Weinhart, T. and Thornton, A.R. and Luding, S. and Bokhove, O. From discrete particles to continuum fields near a boundary. Granular Matter 2012 (1) 1-6 Download
5. Thornton, A.R. and Weinhart, T. and Bokhove, O. and Zhang, B. and van der Sar, D. M. and Kumar, K. and Pisarenco, M. and Rudnaya, M. and Savceno, V. and Rademacher, J. and Zijlstra, J. and Szabelska, A. and Zyprych, J. and van der Schans, M. and Timperio, V. and Veerman, F. (2010) Modeling and optimization of algae growth. In: Proceedings of the 72nd European Study Group Mathematics with Industry, 25-29 Jan 2010, Amsterdam, Netherlands. pp. 54-85. CWI. Download
6. Slimane Adjerid and Thomas Weinhart, Discontinuous Galerkin error estimation for linear symmetrizable hyperbolic systems, AMS, Journal of Mathematics of Computation, 80 (2011) 1335-1367 Download
7. Slimane Adjerid and Thomas Weinhart, Asymptotically Correct Discontinuous Galerkin error estimates for linear symmetric hyperbolic systems, Applied Numerical Mathematics, submitted March 2011
8. Slimane Adjerid and Thomas Weinhart, Discontinuous Galerkin error estimation for linear symmetric hyperbolic systems, Computer Methods in Applied Mechanics and Engineering 2009, 198 (37-40), 3113-3129 Download

1. 17-18 January 2012: FOM, Veldhoven, NL
2. 13 January 2012: Burgersdag, Delft, NL
3. 26 October 2011: Particles 2011, Barcelona, ES
4. 23 October 2011: EM 2011, Lunteren, NL (Poster)
5. 27 September 2011: ISSI, Bern, CH
6. 11 April 2011: Bristol, UK
7. 3 April 2011: EGU 2011, Vienna (Poster)
8. 20 October 2010: Fermat-Impact-Gimfus, Sevilla, ES
9. 29 September 2010: SIP1 Workshop, Enschede, NL
10. 14 July 2010: ECCOMAS, Lisbon, PT (Poster)
11. 14 March 2010: Virginia Tech, Blacksburg, VA, US

Courses Thomas Weinhart taught in

2012

Programming in Engineering (Summer, Fall): General Info, Script

From particles to continuum - Micro-Macro Methods (Spring) General Info

2011

Advanced Programming in Engineering (Fall): General Info, Script

Programming in Engineering (Fall): General Info, Script

2010

Advanced Programming in Engineering (Fall)

From particles to continuum - Micro-Macro Methods (Spring) General Info

Programming in Engineering (Summer)

07/15/2011
Text 'quote'

Welcome to Thomas Weinhart's homepage