Scientific Report

(full version)


The main aim of the 'Physics with Industry workshop' was to obtain creative solutions for industrial problems and to bring (young) physicists in contact with industrial R&D. The workshop was inspired by the 'Mathematics with Industry' workshops, which have regularly been organised by the 'International Study Group Mathematics with Industry' since 1968.


Sixty-seven physicists participated in the workshop, ranging from PhD students to pro¬fessors. These scientists spent a week working in groups on five industrial problems, which were selected by a programme committee from proposals put forward by indus¬try. Following an introduction to the various problems by the companies on Monday, the participants worked on these in groups for the rest of the week. On the last day, the groups presented their findings to the companies.


Besides the scientific outcomes, the workshop also resulted in new collaborations and researchers were approached by recruiters of the participating companies. Participants were mostly driven by the shear pleasure of applying their physics knowledge to new problems, the desire to enrich their scientific network and the interest in gaining hands on experience with industrial R&D processes. Companies benefited from the scientific input they received and participating in the workshop enlarged their academic network. The organisation captured the scientific results in the Proceedings, that can be down loaded from Besides these proceedings a booklet (in Dutch) was made that gives a look and feel of the workshop week.


Based on the results reported in this document and the highly positive feedback received from both industrial and academic participants about the week, the organising commit¬tee aims at organizing another 'Physics with Industry' workshop in October 2011.

ASML case: Droplet removal with impinging planar micro jets

A strategy is proposed to model the interaction between normally impinging laminar jet flow ( ) and water droplets. First, the hodograph method is adopted to compute the inviscid flow at the impingement plate. The wall pressure is computed with Bernoulli's principle. The wall shear stress follows from a boundary layer development by Thwaites method. The shear layer at the free stream line is assumed to grow like the shear layer between a parallel uniform and stagnant flow. These results are combined to define a first-order velocity profile at distance   from the stagnation point and beyond, with   the width of the nozzle exit. First attempts to match this first-order solution to Glauert's self-similarity solution for the laminar wall jet turned out unsuccessful. The gas flow models are used to compute the wall stresses. These serve as input for estimating the drag force exerted on a droplet in impinging gas flow. Because of mathematical difficulties, this part of the original problem is simplified. We adopt a purely 2D geometry and fix impingement plate (i.e. no relative motion between droplet and plate). We extend existing lubrication models to deal with interface shear stress. The next step is to extend such models to 3D and add relative motion between plate and droplet.


NXP case: Protecting high frequency IC's from ElectroStatic Discharge

NXP aims to develop electronic circuits that can improve our everyday energy efficiency, connectivity, and security. One of the challenges the company is facing is Electrostatic discharge (ESD) as it damages integrated circuits (IC's). Devices for ESD protection should drain charge in a very short time (~10 ns), to prevent high voltages to build up over the sensitive IC's. Additionally, these devices should have low capacitances to prevent high frequency signals to leak to ground. These requirements make it challenging to produce protective devices for high frequency IC's.

We found three types of devices which could possibly be used to protect high frequency IC's, namely field emission devices, spark gaps devices, and electrostatic switches. With the help of strongly simplified models we have approximated the performance of these devices.


NIZO case: Water water interfaces

One of the key objectives in food research is the understanding under which conditions water-water emulsions are stable. It is often desirable from an environmental point of view to replace organic solvents by water. Also, the increased demand for low-fat food products leads to the question to what extent water-water emulsions can replacewater-oil emulsions. The NIZO research question posed to the physics community is therefore to find surfactant-like molecules that sit at the water-water interface. The surfactant-like molecules may then be tailored (1) to make sure that there is a repulsion between emulsion droplets (by adding charge, etc) necessary for stability, (2) to change the rigidness of the emulsion droplet’s surface. The formulation of a theoretical framework to understand the properties of the water-water interface is therefore our main goal.


Teijin case: The homogeneity of yarn in the heat treatment section of the production process of Twaron®

The heat treatment section of Twaron® production consists of a series of heated rolls with different temperatures and rolling speeds. This part of the production line provides heat transfer required for drying the yarn, and a controlled increase and decrease of yarn tension required for enhancing the stiffness of the yarn. The analysis of this process was split into two tasks.

In task 1 the heat transfer and the evaporation of the free water and the moisture are described. The results from this theoretical description comply reasonably with results from experiments and on-site results. Especially the description of the drying of the filaments still has some weaknesses. Suggestions were given on changing roll temperatures for controlling boiling and drying of the filaments, and for improving the modelling of the filament drying process.

In task 2 the dynamics of the yarn running over the rolls is considered. First, a possible mechanism is proposed for the formation of 'loops' in the final yarn product, which is based on the inhomogeneous heat treating, hence stiffening on the rolls. Combined with a positive feedback, which forces the stiffer fibres to be closer to the hot roll surface in all subsequent roll passes, this leads to inhomogeneities in both filament stiffness and filament length. An experiment to check this is proposed. Secondly, the classical 'belt friction equation' was reconsidered. Especially stick-slip phenomena were described by cutting down the contact area with the roll surface into a large but finite set of mass-spring systems. The dynamic behaviour was simulated in a computer model. Average tension profiles and their statistics were predicted, and according experiments to check these were suggested.

The problem in its original form has not been solved, however a few possible directions for further study have been given, based on desktop (theoretical) work as well as based on experiments that can be carried out in the Arnhem test-site.


FrieslandCampina case : Schrödinger's Capsule: a (micro)capsulate that is open and closed at the same time

We exploit different routes for encapsulation of food additives, such as minerals or vitamins, in a polymeric capsule. The added active ingredients should remain inside the capsule for at least a year in an aqueous environment (e.g. a dairy product), since sensory properties or functionality of the ingredients may otherwise be affected. However, after intake the active compound should readily (within 1 h) be released due to the acidic environment in the stomach. First, we propose a phenomenological model in order to study how a polymeric matrix may limit the diffusion of incorporated active molecules. The relation between the release rate of the active compound and its molecular weight is elucidated. Second, the desired capsules may be obtained by specific binding between subunits within the capsule and the active ingredient. We show two examples that rely on this mechanism: amylose-lipid complexes and mixed metal hydroxides. Amylose is able to form inclusion complexes with various types of ligands, including iodine, monoglycerides, fatty acids and alcohols, where the hydrophobic parts of the ligands are entrapped in the hydrophobic helical cavity of amylose. Mixed metal hydroxides are a versatile class of inorganic solids that consist of sheets of metal cations that are octahedrally surrounded by hydroxide molecules. In between these layers anionic species compensate for charge neutrality. In this way, various metal cations (minerals) may be incorporated with a high loading, and negatively charged actives may be placed between the layers. Upon digestion the particles dissolve and the ingredients are digested. Finally, we show that nature has already developed many intriguing capsules.