What is it about?
Dissipative particle dynamics (DPD) is a computer method where groups of atoms are modelled as soft blobs. Here we use DPD to represent polymers (long chain molecules) in a solvent and explore two different methods to calculate the viscosity (thickness) of the fluid. We find that these methods give the same results, however, one has a lower amount of error and so should be used.
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Photo by Adrien Converse on Unsplash
Why is it important?
We compare two approaches to calculate the viscosity at equilibrium, that is, without shearing or moving the system. This is important to understand the thickness of a system without any force on, like the shampoo in the bottle. Usual computer methods shear the system and have to extrapolate back to get this value, which doesn't always hold as the structures might not be the same in the two conditions. By comparing the techniques together and with literature values we validate this approach. We also find that one method give less error and so it should be used in future work.
Perspectives
This work arose from a question for a much more complex system - which approach should we use? And so it demonstrates the importance of thinking and planning carefully before jumping straight in!
Dr Charlie Wand
University of Exeter
Read the Original
This page is a summary of: Comparison of equilibrium techniques for the viscosity calculation from DPD simulations, Soft Matter, January 2021, Royal Society of Chemistry,
DOI: 10.1039/d1sm00891a.
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