Person:
Martín Roca, José

Profile Picture
First Name
José
Last Name
Martín Roca
URI
https://hdl.handle.net/20.500.14352/85736
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Físicas
Department
Estructura de la Materia, Física Térmica y Electrónica
Area
Identifiers
UCM identifierScopus Author IDDialnet ID

Filters

2022 - 20232
Reset filters

Settings

Author: Bianco, Valentino ×

Search Results

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Simulating Microswimmers Under Confinement With Dissipative Particle (Hydro) Dynamics
    (Frontiers in physics, 2022) Barriuso Gutiérrez, Carlos Miguel; Martín Roca, José; Bianco, Valentino; Pagonabarraga, Ignacio; Valeriani, Chantal
    In this work we study microwimmers, whether colloids or polymers, embedded in bulk or in confinement. We explicitly consider hydrodynamic interactions and simulate the swimmers via an implementation inspired by the squirmer model. Concerning the surrounding fluid, we employ a Dissipative Particle Dynamics scheme. Differently from the Lattice-Boltzmann technique, on the one side this approach allows us to properly deal not only with hydrodynamics but also with thermal fluctuations. On the other side, this approach enables us to study microwimmers with complex shapes, ranging from spherical colloids to polymers. To start with, we study a simple spherical colloid. We analyze the features of the velocity fields of the surrounding solvent, when the colloid is a pusher, a puller or a neutral swimmer either in bulk or confined in a cylindrical channel. Next, we characterise its dynamical behaviour by computing the mean square displacement and the long time diffusion when the active colloid is in bulk or in a channel (varying its radius) and analyze the orientation autocorrelation function in the latter case. While the three studied squirmer types are characterised by the same bulk diffusion, the cylindrical confinement considerably modulates the diffusion and the orientation autocorrelation function. Finally, we focus our attention on a more complex shape: an active polymer. We first characterise the structural features computing its radius of gyration when in bulk or in cylindrical confinement, and compare to known results obtained without hydrodynamics. Next, we characterise the dynamical behaviour of the active polymer by computing its mean square displacement and the long time diffusion. On the one hand, both diffusion and radius of gyration decrease due to the hydrodynamic interaction when the system is in bulk. On the other hand, the effect of confinement is to decrease the radius of gyration, disturbing the motion of the polymer and thus reducing its diffusion.
  • Thumbnail Image
    Item
    Rheology of Pseudomonas fluorescens biofilms: From experiments to predictive DPD mesoscopic modeling
    (Journal of chemical physics, 2023) Martín Roca, José; Bianco, Valentino; Alarcón, Francisco; Monnappa, Ajay K.; Natale, Paolo; Monroy, Francisco; Orgaz Martín, Belén; López Montero, Iván; Valeriani, Chantal
    Bacterial biofilms mechanically behave as viscoelastic media consisting of micron-sized bacteria cross-linked to a self-produced network of extracellular polymeric substances (EPSs) embedded in water. Structural principles for numerical modeling aim at describing mesoscopic viscoelasticity without losing details on the underlying interactions existing in wide regimes of deformation under hydrodynamic stress. Here, we approach the computational challenge to model bacterial biofilms for predictive mechanics in silico under variable stress conditions. Up-to-date models are not entirely satisfactory due to the plethora of parameters required to make them functioning under the effects of stress. As guided by the structural depiction gained in a previous work with Pseudomonas fluorescens [Jara et al., Front. Microbiol. 11, 588884 (2021)], we propose a mechanical modeling by means of Dissipative Particle Dynamics (DPD), which captures the essentials of topological and compositional interactions between bacterial particles and cross-linked EPS-embedding under imposed shear. The P. fluorescens biofilms have been modeled under mechanical stress mimicking shear stresses as undergone in vitro. The predictive capacity for mechanical features in DPD-simulated biofilms has been investigated by varying the externally imposed field of shear strain at variable amplitude and frequency. The parametric map of essential biofilm ingredients has been explored by making the rheological responses to emerge among conservative mesoscopic interactions and frictional dissipation in the underlying microscale. The proposed coarse grained DPD simulation qualitatively catches the rheology of the P. fluorescens biofilm over several decades of dynamic scaling. Published under an exclusive license by AIP Publishing.