# Jorge Viñals

Director of Graduate Studies

Professor, School of Physics and Astronomy

Contact

130-17 John T. Tate Hall

116 Church Street Se

Minneapolis, MN 55455

Affiliations

# Jorge Viñals

Director of Graduate Studies

Professor, School of Physics and Astronomy

Our research is of theoretical and computational nature, and focuses on mesoscale theories of nonequilibrium phenomena in extended systems, with applications to Statistical Mechanics, Soft Matter Physics, and Materials Science. Generically, systems outside of thermodynamic equilibrium involve unstable interfaces and moving topological defects. We develop theories at the mesoscale of the relevant phases, analyze their macroscopic scale asymptotics, and obtain their non equilibrium properties through large scale computation. Our research is currently motivated by topologically driven flows in liquid crystals, unstable interfaces in complex fluids, and a mesoscale description of plasticity in defected materials.

## Education

Ph.D., University of Barcelona, Spain

## Selected Publications

### Preprints:

**Topological defects, surfaces, and instabilities in liquid crystals**

- The role of Gaussian curvature on local equilibrium and dynamics of smectic-isotropic interfaces.
- Computational molecular field theory for nematic liquid crystals.
- A model of the dynamics of an interface between a smectic phase and an isotropic phase of different density.
- Spiral defect chaos in Rayleigh-Benard convection: Asymptotic and numeric study of azimuthal flows induced by rotating spirals.
- Anisotropic disclination cores in nematic liquid crystals modeled by a self consistent molecular field theory.

**Topological defect motion, microstructure, and stress response in materials**

- Impact of lattice rotation on dislocation motion.
- Dislocation dynamics and crystal plasticity in the phase field crystal model.
- Separation of elastic and plastic time scales in a phase field crystal model.
- A coarse-grained phase-field crystal model of plastic motion.
- Field Dislocation Mechanics and Phase Field Crystal models

**Transport in nematic suspensions**

- Liquid crystals with patterned molecular orientation as an electrolytic active medium.
- Electrokinetic flows in liquid crystal thin films with fixed anchoring
- Nonlinear electrophoresis of colloids controlled by anisotropy of conductivity and permittivity of liquid crystal electrolyte
- Q-tensor model for electrokinetics in nematic liquid crystals.
- Electrokinetic effects in nematic suspensions: Single particle electroosmosis and inter particle interactions.
- A connection between Living Liquid Crystals and electrokinetic phenomena in nematic fluids.

**Publications**

**2023**

Schimming, C., **Viñals, J.** (2023). Kinematics and dynamics of disclination lines in three-dimensional nematics. *Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences*. *479* (2273), [20230042].

DOI: 10.1098/rspa.2023.0042

**2022**

Skogvoll, V., Angheluta, L., Skaugen, A., Salvalaglio, M., **Viñals, J.** (2022). A phase field crystal theory of the kinematics of dislocation lines. *Journal of the Mechanics and Physics of Solids*. [104932].

DOI: 10.1016/j.jmps.2022.104932

Acharya, A., Angheluta, L., **Viñals, J.** (2022). Elasticity versus phase field driven motion in the phase field crystal model. *Modelling and Simulation in Materials Science and Engineering*. *30* (6), [064005].

DOI: 10.1088/1361-651X/ac860b

Schimming, C., **Viñals, J.** (2022). Equilibrium morphology of tactoids in elastically anisotropic nematics. *Soft Matter*. *18* (41), [8024-8033].

DOI: 10.1039/d2sm00323f

Schimming, C., **Viñals, J.** (2022). Singularity identification for the characterization of topology, geometry, and motion of nematic disclination lines. *Soft Matter*. *18* (11), [2234-2244].

DOI: 10.1039/d1sm01584b

**2021**

Skogvoll, V., Skaugen, A., Angheluta, L., **Viñals, J.** (2021). Dislocation nucleation in the phase-field crystal model. *Physical Review B*. *103* (1), [014107].

DOI: 10.1103/PhysRevB.103.014107

Schimming, C., **Viñals, J.**, Walker, S.W. (2021). Numerical method for the equilibrium configurations of a Maier-Saupe bulk potential in a Q-tensor model of an anisotropic nematic liquid crystal. *Journal of Computational Physics*. [110441].

DOI: 10.1016/j.jcp.2021.110441

Vitral, E., Leo, P.H., **Viñals, J.** (2021). Phase-field model for a weakly compressible soft layered material: morphological transitions on smectic-isotropic interfaces. *Soft Matter*. *17* (25), [6140-6159].

DOI: 10.1039/d1sm00488c

**2020**

Salvalaglio, M., Angheluta, L., Huang, Z.F., Voigt, A., Elder, K.R., **Viñals, J.** (2020). A coarse-grained phase-field crystal model of plastic motion. *Journal of the Mechanics and Physics of Solids*. [103856].

DOI: 10.1016/j.jmps.2019.103856

Schimming, C., **Viñals, J.** (2020). Anisotropic disclination cores in nematic liquid crystals modeled by a self-consistent molecular field theory. *Physical Review E*. *102* (1), [010701].

DOI: 10.1103/PhysRevE.102.010701

Schimming, C.D., **Viñals, J.** (2020). Computational molecular field theory for nematic liquid crystals. *Physical Review E*. *101* (3), [032702].

DOI: 10.1103/PhysRevE.101.032702

Gaudreault, M., Drolet, F., **Vinãls, J.** (2020). Erratum: Bifurcation threshold of the delayed van der Pol oscillator under stochastic modulation [Phys. Rev. e 85, 056214 (2012)]. *Physical Review E*. *101* (2), [029901].

DOI: 10.1103/PhysRevE.101.029901

Acharya, A., **Viñals, J.** (2020). Field dislocation mechanics and phase field crystal models. *Physical Review B*. *102* (6), [064109].

DOI: 10.1103/PhysRevB.102.064109

Vitral, E., Leo, P.H., **Vinãls, J.** (2020). Model of the dynamics of an interface between a smectic phase and an isotropic phase of different density. *Physical Review Fluids*. *5* (7), [073302].

DOI: 10.1103/PhysRevFluids.5.073302

Vitral, E., Mukherjee, S., Leo, P.H., **Viñals, J.**, Paul, M.R., Huang, Z.F. (2020). Spiral defect chaos in Rayleigh-Bénard convection: Asymptotic and numerical studies of azimuthal flows induced by rotating spirals. *Physical Review Fluids*. *5* (9), [093501].

DOI: 10.1103/PhysRevFluids.5.093501

**2019**

Vitral, E., Leo, P.H., **Viñals, J.** (2019). Role of Gaussian curvature on local equilibrium and dynamics of smectic-isotropic interfaces. *Physical Review E*. *100* (3), [032805].

DOI: 10.1103/PhysRevE.100.032805

**2018**

Conklin, C., **Viñals, J.**, Valls, O.T. (2018). A connection between living liquid crystals and electrokinetic phenomena in nematic fluids. *Soft Matter*. *14* (22), [4641-4648].

DOI: 10.1039/c7sm02492d

Skaugen, A., Angheluta, L., **Viñals, J.** (2018). Dislocation dynamics and crystal plasticity in the phase-field crystal model. *Physical Review B*. *97* (5), [054113].

DOI: 10.1103/PhysRevB.97.054113

Conklin, C., Tovkach, O.M., **Viñals, J.**, Calderer, M.C., Golovaty, D., Lavrentovich, O.D., Walkington, N.J. (2018). Electrokinetic effects in nematic suspensions: Single-particle electro-osmosis and interparticle interactions. *Physical Review E*. *98* (2), [022703].

DOI: 10.1103/PhysRevE.98.022703

Skaugen, A., Angheluta, L., **Viñals, J.** (2018). Separation of Elastic and Plastic Timescales in a Phase Field Crystal Model. *Physical review letters*. *121* (25), [255501].

DOI: 10.1103/PhysRevLett.121.255501

**2017**

Conklin, C., **Viñals, J.** (2017). Electrokinetic flows in liquid crystal thin films with fixed anchoring. *Soft Matter*. *13* (4), [725-739].

DOI: 10.1039/c6sm02393b

Paladugu, S., Conklin, C., **Viñals, J.**, Lavrentovich, O.D. (2017). Nonlinear Electrophoresis of Colloids Controlled by Anisotropic Conductivity and Permittivity of Liquid-Crystalline Electrolyte. *Physical Review Applied*. *7* (3), [034033].

DOI: 10.1103/PhysRevApplied.7.034033

Tovkach, O.M., Conklin, C., Calderer, M.C., Golovaty, D., Lavrentovich, O.D., **Viñals, J.**, Walkington, N.J. (2017). Q-tensor model for electrokinetics in nematic liquid crystals. *Physical Review Fluids*. *2* (5), [053302].

DOI: 10.1103/PhysRevFluids.2.053302

**2016**

Perreault, B., **Viñals, J.**, Rickman, J.M. (2016). Impact of lattice rotation on dislocation motion. *Physical Review B*. *93* (1), [014107].

DOI: 10.1103/PhysRevB.93.014107

**2015**

Lavrentovich, O.D., Peng, C., Guo, Y., Shiyanovskii, S., Wei, Q., **Vinals, J.**, Conklin, C. (2015). Liauid crystal enabled electrokinetics. In Annual Meeting of the American Electrophoresis Society 2015, AES 2015 - Topical Conference at the 2015 AIChE Annual Meeting. (161-171). (Annual Meeting of the American Electrophoresis Society 2015, AES 2015 - Topical Conference at the 2015 AIChE Annual Meeting.). AIChE.

Peng, C., Guo, Y., Conklin, C., **Viñals, J.**, Shiyanovskii, S.V., Wei, Q.H., Lavrentovich, O.D. (2015). Liquid crystals with patterned molecular orientation as an electrolytic active medium. *Physical Review E - Statistical, Nonlinear, and Soft Matter Physics*. *92* (5), [052502].

DOI: 10.1103/PhysRevE.92.052502

**2013**

Yoo, C.D., **Viñals, J.** (2013). The role of viscoelastic contrast in orientation selection of block copolymer lamellar phases under oscillatory shear. *Soft Matter*. *9* (32), [7817-7831].

DOI: 10.1039/c3sm00099k

**2012**

Yoo, C.D., **Viñals, J.** (2012). Anisotropic linear response in block copolymer lamellar phases. *Macromolecules*. *45* (11), [4848-4856].

DOI: 10.1021/ma300547y

Gaudreault, M., Drolet, F., **Viñals, J.** (2012). Bifurcation threshold of the delayed van der Pol oscillator under stochastic modulation. *Physical Review E - Statistical, Nonlinear, and Soft Matter Physics*. *85* (5), [056214].

DOI: 10.1103/PhysRevE.85.056214

**2011**

Gaudreault, M., Berbert, J.M., **Viñals, J.** (2011). Correlation times in stochastic equations with delayed feedback and multiplicative noise. *Physical Review E - Statistical, Nonlinear, and Soft Matter Physics*. *83* (1), [011903].

DOI: 10.1103/PhysRevE.83.011903

**2010**

Gaudreault, M., Drolet, F., **Viñals, J.** (2010). Analytical determination of the bifurcation thresholds in stochastic differential equations with delayed feedback. *Physical Review E - Statistical, Nonlinear, and Soft Matter Physics*. *82* (5), [051124].

DOI: 10.1103/PhysRevE.82.051124

**2009**

Gaudreault, M., **Viñals, J.** (2009). Collapse transition of a hydrophobic self-avoiding random walk in a coarse-grained model solvent. *Physical Review E - Statistical, Nonlinear, and Soft Matter Physics*. *80* (2), [021916].

DOI: 10.1103/PhysRevE.80.021916

**Viñals, J.** (2009). Defect dynamics in mesophases. *Journal of the Physical Society of Japan*. *78* (4), [041011].

DOI: 10.1143/JPSJ.78.041011

Gaudreault, M., Lépine, F., **Viñals, J.** (2009). Pitchfork and Hopf bifurcation thresholds in stochastic equations with delayed feedback. *Physical Review E - Statistical, Nonlinear, and Soft Matter Physics*. *80* (6), [061920].

DOI: 10.1103/PhysRevE.80.061920

**2008**

Tamate, R., Yamada, K., **Viñals, J.**, Ohta, T. (2008). Structural rheology of microphase separated diblock copolymers. *Journal of the Physical Society of Japan*. *77* (3), [034802].

DOI: 10.1143/JPSJ.77.034802

**2007**

Yeh, S.S., Hsueh, C., Chen, P., **Viñals, J.** (2007). Field-induced columnar structures in a quasi-two-dimensional system of dipolar particles. *Physical Review E - Statistical, Nonlinear, and Soft Matter Physics*. *76* (5), [051407].

DOI: 10.1103/PhysRevE.76.051407

Huang, Z.F., **Viñals, J.** (2007). Grain boundary dynamics in stripe phases of nonpotential systems. *Physical Review E - Statistical, Nonlinear, and Soft Matter Physics*. *75* (5), [056202].

DOI: 10.1103/PhysRevE.75.056202

Huang, Z.F., **Viñals, J.** (2007). Stability of parallel/perpendicular domain boundaries in lamellar block copolymers under oscillatory shear. *Journal of Rheology*. *51* (1), [99-123].

DOI: 10.1122/1.2399088

**2006**

Huang, Z.F., **Viñals, J.** (2006). Orientation selection in lamellar phases by oscillatory shears. *Physical Review E - Statistical, Nonlinear, and Soft Matter Physics*. *73* (6), [060501].

DOI: 10.1103/PhysRevE.73.060501

**2005**

Huang, Z.F., **Viñals, J.** (2005). Tilt grain boundary instabilities in three-dimensional lamellar patterns. *Physical Review E - Statistical, Nonlinear, and Soft Matter Physics*. *71* (3), [031501].

DOI: 10.1103/PhysRevE.71.031501

Rickman, J.M., **Viñals, J.**, Lesar, R. (2005). Unified framework for dislocation-based defect energetics. *Philosophical Magazine*. *85* (9), [917-929].

DOI: 10.1080/14786430412331314618

**2004**

Vega, J.M., Rüdiger, S., **Viñals, J.** (2004). Phenomenological model of weakly damped Faraday waves and the associated mean flow. *Physical Review E - Statistical, Nonlinear, and Soft Matter Physics*. *70* (4 2), [046306]. [046306-1-046306-18].

DOI: 10.1103/PhysRevE.70.046306

Huang, Z.F., **Viñals, J.** (2004). Shear-induced grain boundary motion for lamellar phases in the weakly nonlinear regime. *Physical Review E - Statistical, Nonlinear, and Soft Matter Physics*. *69* (4), [041504].

DOI: 10.1103/PhysRevE.69.041504

**2003**

Huang, Z.F., Drolet, F., **Viñals, J.** (2003). Motion of a transverse/parallel grain boundary in a block copolymer under oscillatory shear flow. *Macromolecules*. *36* (25), [9622-9630].

DOI: 10.1021/ma034083q

**2002**

Boyer, D., **Viñals, J.** (2002). Grain boundary pinning and glassy dynamics in stripe phases. *Physical Review E - Statistical, Nonlinear, and Soft Matter Physics*. *65* (4), [046119]. [046119/1-046119/12].

DOI: 10.1103/PhysRevE.65.046119

Chen, P., **Viñals, J.** (2002). Lamellar phase stability in diblock copolymers under oscillatory shear flows. *Macromolecules*. *35* (10), [4183-4192].

DOI: 10.1021/ma011586s

Mullins, W.W., **Viñals, J.** (2002). Linear bubble model of abnormal grain growth. *Acta Materialia*. *50* (11), [2945-2954].

DOI: 10.1016/S1359-6454(02)00121-0

**Viñals, J.**, Kolinski, A., Skolnick, J. (2002). Numerical study of the entropy loss of dimerization and the folding thermodynamics of the GCN4 leucine zipper. *Biophysical journal*. *83* (5), [2801-2811].

DOI: 10.1016/S0006-3495(02)75289-2

Boyer, D., **Viñals, J.** (2002). Weakly nonlinear theory of grain boundary motion in patterns with crystalline symmetry. *Physical review letters*. *89* (5), [055501]. [055501/1-055501/4].

DOI: 10.1103/PhysRevLett.89.055501

**2001**

Drolet, F., **Viñals, J.** (2001). Adiabatic elimination and reduced probability distribution functions in spatially extended systems with a fluctuating control parameter. *Physical Review E - Statistical, Nonlinear, and Soft Matter Physics*. *64* (2), [026120]. [261201-261208].

DOI: 10.1103/PhysRevE.64.026120

### Graduate Students

- Lucas Myers
- Cody Schimming