Determination of the shear and bulk viscosity from equilibrium molecular-dynamics simulations*

Determining fluid properties accurately is essential for large-scale fluid dynamics simulations where only a few parameters determine the behaviour of an entire system. Even though many properties are well known, others are more obscure and difficult to determine experimentally. One such property is the bulk viscosity which plays a particularly large role in compressible fluids but is rarely considered in fluid-dynamics simulations. We determine both the shear and bulk viscosity using equilibrium methods within the molecular-dynamics framework using both atomistic and coarse-grained models with a view of assessing both the accuracy of coarse-grained models for transport-property calculations and the necessity of including such properties at various scales and scenarios.