Process design

Simulation of grinding mill with brick fragments

 

 

It is estimated that around 80% of all industrial processes deal with particulate materials. Some examples are conveyor belts, hoppers, mixers, cyclones and tabletting machines. The Mpacts software is able to simulate these processes and predict the effectiveness of different design options. By doing so, the cost for prototyping can be decreased or even removed entirely. Moreover, many particulate flows can suddenly exhibit process-critical behavior, such as blockage, jamming, fracture or fragmentation. These phenomena are very hard to predict using the continuum approximations that are adopted in classical CFD simulations. DEM simulations have to potential to help design industrial processes that either avoid or harness these complex system properties.

Example: Milling operations

This figures shows a milling simulation, where arbitrarily shaped particles are placed in a rotating drum. Typically, an abrasive action is desired on the particles, induced by the rotational motion of the mill.

Simulations can help answer a range of questions during the design phase of these milling machines. DEM simulations can predict the distribution of impact energies. With this information available, the mill can be either optimised to be as 'aggressive' as possible, or if only partial destruction is desired, e.g. when separating materials rather than milling it, an optimal impact distribution may be computed.

Another very common problem is process upscaling. How do the forces scale when a working-lab scale equipment is scaled up to an industrial scale? What are the new optimal setpoints for the rotational velocity, and how do we have to modify the industrial design to mimick the lab  scale conditions as closely as possible?

Fruit and crop handling

Example: Agricultural Machinery

As mobile platforms that perform mechanical operations on crops, agricultural machines benefit greatly from design changes that improve production output and/or reduce fuel consumption rates.

Moreover, they are often required to handle fragile biological materials for which mechanical damage/bruising can incur significant economic losses. The granular nature of these operations with complicated shapes and non-linear, history-dependent and soft mechanical behavior has hindered the widespread adoption of simulation-based computer aided product and process design. The software Mpacts is uniquely suited for simulating these systems, due to its capability of representing arbitrary and deformable shapes, its data-based material descriptions, and its innate extensibility. For example, crops can be represented as flexible rods composed out of capsule geometries, of which the mechanical behavior is calibrated based on a few inexpensive lab experiments (see image).

For a given machine design, simulations can predict how the crop flow influences the power consumption, which machine components are most likely to wear quickly, and how efficiently the crop is being processed.

Bulk compression of crop stems
Mpacts - crop processing
Simulation of pears in a box, damaged by transportation

Example: Fruit bruise reduction

Bruise damage in fruits and vegetables is an important source of economic losses and food waste. Especially soft fruits are very susceptible to bruises. Simulations using Mpacts with virtual fruit and vegetables are a powerful and cost-effective approach for improving fruit and crop handling.

For example, they can help guide the design of an optimal picking gripper for different fruit shapes. Simulations can also provide insight in the critical frequencies and amplitudes that should be avoided during transport. Using that knowledge, transport vehicles can be adjusted or packaging techniques and materials can be imporoved in order to obtain better damping of damaging vibrations.

http://dx.doi.org/10.1016/j.postharvbio.2016.06.003

Discrete Element Method simulations can help design sorting lines, and not only to help prevent bruise damage. Simulations of the fruit singulator in sorting lines can be used to examine at which rotational speed or with what type of diabolo a good singulation and fruit alignment can be realized.

Biotech

Recent years have seen an elevated focus on tissue engineering, tissue/organ bio-printing, microfluidics, and lab-on-a-chip technologies which are characterized by bottom-up development strategies and an increased importance of controlling and manipulating inter-cellular interactions.

Particle-based simulations can aid the design of devices for manipulation, transport and manufacturing of cellular systems in industrial processes. For example, they can help devise microfluidic channels that efficiently transport cells while preventing jamming or flocculation.

This figure shows a simulation of budding yeast (saccharomyces cerevisiae) forming multicellular clusters (called flocs) in shear flow conditions. Industrially, flocculation in yeast is harnessed in beer brewing processes, where large flocs of yeast cells either settle at the bottom or float towards the top of a brew. Thereby, the yeast can be efficiently removed from the product.

Flocculation in suspensions of yeast cells

Large machine design

Example: load prediction on icebreaker hull

Icebreakers are needed to keep trade routes open where there are either seasonal or permanent ice conditions. While merchant vessels calling ports in these regions are strengthened for navigation in ice, they are usually not powerful enough to manage the ice by themselves.

Icebreakers clear paths by pushing straight into ice pockets. The bending strength of sea ice is often so low that the ice breaks without noticeable change in the vessel's trim. In cases of thick ice, an icebreaker can drive its bow onto the ice to break it under the weight of the ship. Because a buildup of broken ice in front of a ship can slow it down much more than the breaking of the ice itself, icebreakers require a specially designed hull to direct the broken ice around or under the vessel.
The external components of the ship's propulsion system (propellers, propeller shafts, etc.) are also at risk of damage, so the ability of an icebreaker to propel itself onto the ice, break it, and clear the debris from its path is essential for its safety.

To meet these requirements, Mpacts software can help improve the ships design by simulating its interactions with the ice and the breaking of the ice.

Icebreaker