Computational methods and tool for complex suspensions will take place from 23 to 27 May 2022 in Bilbao at Ensanche Building, located in Pl. del Ensanche, 11, 48009 Bilbao, Vizcaya.

The workshop’s alternative concept is based on two objectives: foster connections between theory, computation, and experiments and to be a forum for sharing open, unresolved problems, new ideas, and hypotheses.

Suspensions of micro and nano particles in simple and complex fluids are ubiquitous in nature. Developing a mathematical and physical understanding of the behavior of such systems under different flow conditions can greatly benefit various fields of engineering and technology. Computer simulations are often the only feasible approach because of the complexity of the geometry, properties, and interactions of the suspended particles, and because it is mandatory to accurately reproduce far-field hydrodynamic and short-range lubrication interactions, the presence of thermal fluctuations consistent with thermodynamics and fluctuation-dissipation balance, each of which alone presents enormous technical challenges. A number of numerical techniques have been developed over multiple decades, yet, even for the well-understood case of monodispersed suspensions of spherical rigid particles interacting through a Newtonian liquid medium, major breakthroughs in creating linear-scaling methods have only been made recently.

Some of these recent state-of-the-art computational methods have yet to reach the soft-matter, computational biology, and chemical engineering communities, to name a few. At the same time, computational scientists and applied mathematicians developing new techniques are often not aware of the latest experimental progress on understanding synthetic and biological suspensions. The workshop’s alternative concept is based on two objectives: i) foster connections between theory, computation, and experiments and ii) to be a forum for sharing open, unresolved problems, new ideas, and hypotheses.

The scientific goal of this workshop is to move beyond so-called “simple suspensions” to “complex suspensions” where complexity can come from different (possibly concomitant) sources that include but are not restricted to:

1- Non-Newtonian properties of suspending phases

Many techniques have been developed in the past decades to target suspensions with simple Newtonian solvents. How can computational models be generalized to handle viscoelastic, plastic, or thinning/thickening liquid phases? How can far-field hydrodynamics interactions between suspended particles be modelled accurately and efficiently? Can new short-range non-Newtonian lubrication force models be developed? How can we model partial/full slippage effects on the particle surface, and translate them into effective hydrodynamic interactions? How can the above mentioned non-Newtonian models be generalized to the fluctuating/Brownian regime? This topic will also include contact frictional interactions and tribological effects.

2 – Complexity of the dispersed phase, particle anisotropy and deformability

In applications in engineering and biology, suspensions are often composed of deformable and anisotropic particles. Examples include blood cells, actin and microtubule filaments in the cell cytoskeleton, multiphase droplets, misceles, nonspherical colloids, mixtures of polymers and colloids, and many others.  Topics of specific interest include novel models and numerical schemes for suspensions of irregularly-shaped particles (including roughness), deformable particles, including Brownian motion, as well as applications in biophysics or technology/engineering.

3 – Complex inter-particle interactions and multiphysics

It is well known that non-hydrodynamic interactions also play a crucial role in the suspension microdynamics, diffusion, rheology and collective dynamics. Novel schemes and/or applications focusing on the effect of complex non-hydrodynamic interactions in suspensions will also be covered in this workshop. We plan to exchange information with disciplines involving many-body interactions such as magnetic nanoparticles or dielectric nanoparticles under optical fields. This topic will also includes short-range complex reversible interactions (e.g., DNA-coated colloids).

Other sources of suspension complexity of current interest may also be represented, notably particle activity driven either by particle deformations, complex interactions such as chemistry, or external fields.