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
Courses Thomas Weinhart taught in
Programming in Engineering (Summer, Fall):
General Info,
Script
From particles to continuum - Micro-Macro Methods (Spring)
General Info
Advanced Programming in Engineering (Fall):
General Info,
Script
Programming in Engineering (Fall):
General Info,
Script
Advanced Programming in Engineering (Fall)
From particles to continuum - Micro-Macro Methods (Spring)
General Info
Programming in Engineering (Summer)