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The Role of Engineering Technologies: Virtual Prototyping

By: Brian Bell, Peter Spicka and Aniruddha Mukhopadhyay
Posted: October 14, 2008, from the May 2006 issue of GCI Magazine.

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The CFD model in this case consists of several strands of hair very close to the scalp.

In the first example, a comparison is made of the removal of a mixture of grease and dirt from the hair using water and then a water/shampoo mixture. The dirt/grease is modeled as a viscous liquid. At the start of the simulation, droplets of dirt/grease are present on the hair. An initial simulation was performed using pure water only, which does not affect the dirt/grease surface tension or contact angle. The two images in Figure 3, taken from the beginning and end of the simulation, show that very little dirt/grease was removed.

A second simulation was performed using a flow of water/shampoo mixture (containing the 2% detergent). Because the detergent lowers the surface tension of the dirt/grease, the flow of shampoo/water is very effective at removing the dirt as shown by the images in Figure 4, which represent several snapshots in time from the CFD simulation.

In the second example, a simulation is performed of the time-dependent wicking/penetration of a medication (antidandruff agent, for example) into the scalp as it is delivered in a shampoo/water mixture. The concentration of medication in the shampoo/water mixture is assumed to be 1%. Such rudimentary models can be used to obtain a better understanding of the roles of diffusion; convection and capillary effects on the cleaning and delivery effectiveness of various hair-care products.

Through these examples and an analysis of the market factors driving this industry, it is shown that the use of CFD can help companies create more optimal (or “perfect”) products by helping to reduce time-to-market by reducing the time required for physical testing while providing a high level of return on investment, by understanding how unit operations in process equipment affect product quality and by gaining insight into product performance.