Monday, September 14th, 2026
Workshop: Michal Shavit
Time: 9:30 AM - 10:30 AM
Location: SCGP 102
Title: This is my talk
Speaker: Michal Shavit
Abstract: this is my abstract
Title: This is my talk
Speaker: Michal Shavit
Abstract: this is my abstract
Workshop: Anuj Kumar
Time: 11:00 AM - 12:00 PM
Location: SCGP 102
Title:
Speaker: Anuj Kumar
Abstract:
Title:
Speaker: Anuj Kumar
Abstract:
Math Event: Symplectic Geometry, Gauge Theory, and Low-Dimensional Topology Seminar: Sergey Nersisyan - TBA
Time: 12:30 PM - 1:55 PM
Location: Math P-131
Speaker: Sergey Nersisyan
Abstract: TBA
Speaker: Sergey Nersisyan
Abstract: TBA
Workshop: Dina Soltani Tehrani
Time: 1:00 PM - 2:00 PM
Location: SCGP 102
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Speaker: Dina Soltani Tehrani
Abstract: /span>
Title: /span>
Speaker: Dina Soltani Tehrani
Abstract: /span>
Workshop: Michele Dolce
Time: 2:30 PM - 3:30 PM
Location: SCGP 102
Title: Instability of the 2D Taylor-Green vortex
Speaker: Michele Dolce
Abstract: The 2D Taylor-Green (TG) vortex (aka cellular flow) is the prototypical example of an Euler steady state on T^2 possessing truly two-dimensional features, like elliptic and hyperbolic stagnation points. Its streamfunction, sin(x)sin(y), lives on the second Fourier shell, making it susceptible to large-scale destabilizing mechanisms. Despite the apparent simplicity of the steady state, a proof of its spectral instability has long remained elusive, and was only recently observed numerically. To solve this problem, I will introduce a new criterion to detect unstable eigenvalues for a wide class of linear Hamiltonian operators. We apply this to prove the stability of the TG vortex with respect to odd perturbations. In the subspace of functions even in both variables, we combine our criterion with a rigorous computer-assisted argument to locate two unstable eigenvalues. This fully characterizes the unstable spectrum of the TG vortex and implies nonlinear instability in velocity. This is a joint work with G. Cao-Labora, M. Colombo and P. Ventura.
Title: Instability of the 2D Taylor-Green vortex
Speaker: Michele Dolce
Abstract: The 2D Taylor-Green (TG) vortex (aka cellular flow) is the prototypical example of an Euler steady state on T^2 possessing truly two-dimensional features, like elliptic and hyperbolic stagnation points. Its streamfunction, sin(x)sin(y), lives on the second Fourier shell, making it susceptible to large-scale destabilizing mechanisms. Despite the apparent simplicity of the steady state, a proof of its spectral instability has long remained elusive, and was only recently observed numerically. To solve this problem, I will introduce a new criterion to detect unstable eigenvalues for a wide class of linear Hamiltonian operators. We apply this to prove the stability of the TG vortex with respect to odd perturbations. In the subspace of functions even in both variables, we combine our criterion with a rigorous computer-assisted argument to locate two unstable eigenvalues. This fully characterizes the unstable spectrum of the TG vortex and implies nonlinear instability in velocity. This is a joint work with G. Cao-Labora, M. Colombo and P. Ventura.
Workshop: Tommaso Rosati
Time: 4:00 PM - 5:00 PM
Location: SCGP 102
Title: Lyapunov exponents for linear cocycles driven by stochastic Navier-Stokes
Speaker: Tommaso Rosati
Abstract: We provide the first convergence result for finite time Lyapunov exponents of Passive Scalar Advection and Linearized Stochastic Navier-Stokes (two linear cocycles driven by the stochastic Navier-Stokes equations). The proof is based on establishing unique ergodicity for a Markov process with values in an infinite-dimensional projective space. Uniqueness of the invariant measures requires an extension of asymptotic coupling tools, and proving a generic non-collinearity for passive scalar advection. Joint work with Sam Punshon-Smith.
Title: Lyapunov exponents for linear cocycles driven by stochastic Navier-Stokes
Speaker: Tommaso Rosati
Abstract: We provide the first convergence result for finite time Lyapunov exponents of Passive Scalar Advection and Linearized Stochastic Navier-Stokes (two linear cocycles driven by the stochastic Navier-Stokes equations). The proof is based on establishing unique ergodicity for a Markov process with values in an infinite-dimensional projective space. Uniqueness of the invariant measures requires an extension of asymptotic coupling tools, and proving a generic non-collinearity for passive scalar advection. Joint work with Sam Punshon-Smith.
Tuesday, September 15th, 2026
Workshop: Patrick Diamond
Time: 9:30 AM - 10:30 AM
Location: SCGP 102
Title: Nonlinear processes regulating zonal flow amplitude in collisionless drift-Rossby turbulence
Speaker: Patrick Diamond
Abstract: /span>
Title: Nonlinear processes regulating zonal flow amplitude in collisionless drift-Rossby turbulence
Speaker: Patrick Diamond
Abstract: /span>
Workshop: Gautam Iyer
Time: 1:00 PM - 2:00 PM
Location: SCGP 102
Title:
Speaker: Gautam Iyer
Abstract: /span>
Title:
Speaker: Gautam Iyer
Abstract: /span>
Workshop: Kyle Liss
Time: 2:30 PM - 3:30 PM
Location: SCGP 102
Title:
Speaker: Kyle Liss
Abstract: /span>
Title:
Speaker: Kyle Liss
Abstract: /span>
Workshop: Camilla Nobili
Time: 4:00 PM - 5:00 PM
Location: SCGP 102
Title: From Boundary Layers to Ultimate Scaling: Covariance Design and Transport Bounds in Thermal Convection
Speaker: Camilla Nobili
Abstract: /span>A central question in turbulent thermal convection is how near-wall bound- ary layers and bulk turbulent fluctuations constrain the global heat transport (Nu). In this talk, we explore the scaling bounds of thermal transport using a stochastic framework that bridges kinematic limits with dynamical parameteri- sations.The presentation is divided into two parts. In the first part, we consider a generic, incompressible stochastic velocity field with a given energy budget. In the spirit of wall-to-wall optimal transport (e.g., Hassanzadeh, Chini & Doering, 2014), we show that near-wall geometric decay universally caps transport at an asymptotic limit of Nu ≲ Pe2/3 as Pe → ∞. In the second part, coupling the thermal field to Stokes dynamics, we investigate how specific covariance struc- tures of temperature fluctuations select between classical turbulent regimes. By tuning the spatial covariance matrix, we systematically reconstruct both the Malkus Ra1/3 scaling and the Kraichnan–Spiegel Ra1/2 ”ultimate” regime. This approach provides a direct geometric and statistical mechanism explaining how turbulent correlation lengths in the bulk versus the boundary layer dictate macroscale heat transfer.This work is joint with Franco Flandoli and Theresa Lange.
Title: From Boundary Layers to Ultimate Scaling: Covariance Design and Transport Bounds in Thermal Convection
Speaker: Camilla Nobili
Abstract: /span>A central question in turbulent thermal convection is how near-wall bound- ary layers and bulk turbulent fluctuations constrain the global heat transport (Nu). In this talk, we explore the scaling bounds of thermal transport using a stochastic framework that bridges kinematic limits with dynamical parameteri- sations.The presentation is divided into two parts. In the first part, we consider a generic, incompressible stochastic velocity field with a given energy budget. In the spirit of wall-to-wall optimal transport (e.g., Hassanzadeh, Chini & Doering, 2014), we show that near-wall geometric decay universally caps transport at an asymptotic limit of Nu ≲ Pe2/3 as Pe → ∞. In the second part, coupling the thermal field to Stokes dynamics, we investigate how specific covariance struc- tures of temperature fluctuations select between classical turbulent regimes. By tuning the spatial covariance matrix, we systematically reconstruct both the Malkus Ra1/3 scaling and the Kraichnan–Spiegel Ra1/2 ”ultimate” regime. This approach provides a direct geometric and statistical mechanism explaining how turbulent correlation lengths in the bulk versus the boundary layer dictate macroscale heat transfer.This work is joint with Franco Flandoli and Theresa Lange.
Math Event: Geometry/Topology Seminar: Gilbert Weinstein - Kerr Black Hole Uniqueness
Time: 4:00 PM - 5:15 PM
Location: P-131
Speaker: Gilbert Weinstein
Abstract: The no-hair theorem states that the only asymptotically flat stationary solutions of the Einstein vacuum equations are members of the Kerr family, parametrized by mass and angular momentum. Hawking’s rigidity theorem shows that under the hypothesis of analyticity, any such solution is axially symmetric. For axially symmetric solutions with a single connected event horizon, Robinson (1975) proved that the solution must be Kerr. However, the case of multiple black holes has remained largely open. We settle this longstanding problem and show that stationary, axially symmetric multiple black holes cannot be in equilibrium by studying the associated harmonic maps with prescribed singularities. This is joint work with Qing Han, Marcus Khuri, and Jingang Xiong.
Speaker: Gilbert Weinstein
Abstract: The no-hair theorem states that the only asymptotically flat stationary solutions of the Einstein vacuum equations are members of the Kerr family, parametrized by mass and angular momentum. Hawking’s rigidity theorem shows that under the hypothesis of analyticity, any such solution is axially symmetric. For axially symmetric solutions with a single connected event horizon, Robinson (1975) proved that the solution must be Kerr. However, the case of multiple black holes has remained largely open. We settle this longstanding problem and show that stationary, axially symmetric multiple black holes cannot be in equilibrium by studying the associated harmonic maps with prescribed singularities. This is joint work with Qing Han, Marcus Khuri, and Jingang Xiong.
Wednesday, September 16th, 2026
Workshop: Alexandros Alexakis
Time: 9:30 AM - 10:30 AM
Location: SCGP 102
Title:
Speaker: Alexandros Alexakis
Abstract: /span>
Title:
Speaker: Alexandros Alexakis
Abstract: /span>
Workshop: Renzo Ricca
Time: 11:00 AM - 12:00 PM
Location: SCGP 102
Title:
Speaker: Renzo Ricca
Abstract: /span>
Title:
Speaker: Renzo Ricca
Abstract: /span>
Workshop: Victor Steinberg
Time: 1:00 PM - 2:00 PM
Location: SCGP 102
Title:
Speaker: Victor Steinberg
Abstract: /span>
Title:
Speaker: Victor Steinberg
Abstract: /span>
Workshop: Anna Frishman
Time: 2:30 PM - 3:30 PM
Location: SCGP 102
Title:
Speaker: Anna Frishman
Abstract: /span>
Title:
Speaker: Anna Frishman
Abstract: /span>
Workshop: Timo Schorlepp
Time: 4:00 PM - 5:00 PM
Location: SCGP 102
Title:
Speaker: Timo Schorlepp
Abstract: /span>
Title:
Speaker: Timo Schorlepp
Abstract: /span>
Math Event: Algebraic Geometry Seminar: Eric Jovinelly - Free curves in singular varieties
Time: 4:00 PM - 5:00 PM
Location:
Speaker: Eric Jovinelly
Abstract: Rational curves are intricately linked to the birational geometry of varieties containing them. Certain curves, called free curves, have the nicest deformation properties. However, it is unknown whether mildly singular Fano varieties contain free rational curves in their smooth locus. In this talk, we discuss free curves of higher genus. Using recent results about tangent bundles, we prove that any klt Fano variety has higher genus free curves. We then use the existence of such free curves to get some applications: we prove the existence of free rational curves in terminal Fano threefolds; study the fundamental group of the smooth locus of a Fano variety; and obtain a new characterization of projective space via lengths of extremal rays. This is joint work with Brian Lehmann, Eric Riedl, and Osamu Fujino.
Speaker: Eric Jovinelly
Abstract: Rational curves are intricately linked to the birational geometry of varieties containing them. Certain curves, called free curves, have the nicest deformation properties. However, it is unknown whether mildly singular Fano varieties contain free rational curves in their smooth locus. In this talk, we discuss free curves of higher genus. Using recent results about tangent bundles, we prove that any klt Fano variety has higher genus free curves. We then use the existence of such free curves to get some applications: we prove the existence of free rational curves in terminal Fano threefolds; study the fundamental group of the smooth locus of a Fano variety; and obtain a new characterization of projective space via lengths of extremal rays. This is joint work with Brian Lehmann, Eric Riedl, and Osamu Fujino.
Thursday, September 17th, 2026
Workshop: Greg Eyink
Time: 9:30 AM - 10:30 AM
Location: SCGP 102
Title:
Speaker: Greg Eyink
Abstract: /span>
Title:
Speaker: Greg Eyink
Abstract: /span>
Workshop: Guido Boffetta
Time: 11:00 AM - 12:00 PM
Location: SCGP 102
Title:
Speaker: Guido Boffetta
Abstract: /span>
Title:
Speaker: Guido Boffetta
Abstract: /span>
Workshop: Nir Navon
Time: 1:00 PM - 2:00 PM
Location: SCGP 102
Title:
Speaker: Nir Navon
Abstract: /span>
Title:
Speaker: Nir Navon
Abstract: /span>
Math Event: Colloquium: Gilbert Weinstein - TBA
Time: 2:15 PM - 3:15 PM
Location: Math Tower P-131
Speaker: Gilbert Weinstein
Speaker: Gilbert Weinstein
Workshop: Alexei Maliybaev
Time: 2:30 PM - 3:30 PM
Location: SCGP 102
Title: Perturbative anomalous exponents from Kolmogorov multipliers
Speaker: Alexei Maliybaev
Abstract: /span>Intermittency, manifested through anomalous scaling, remains one of the central unresolved problems in turbulence theory, with few analytical approaches extending beyond idealized linear transport models. We introduce a perturbative framework for anomalous scaling in turbulent transport based on multiplier statistics, rather than zero-mode calculations. We demonstrate the approach using a shell model combining deterministic and Kraichnan-like stochastic components. We reduce the problem to the analysis of a stationary Fokker-Planck equation for Kolmogorov multipliers, defined as ratios of successive scalar amplitudes. Its solution yields the invariant measure through a perturbative expansion around a Gaussian distribution. Using the resulting multiplier statistics, we compute explicit anomalous scaling exponents for structure functions of arbitrary order, including odd, even, and non-integer moments. Although demonstrated here for a shell model, the framework suggests a systematic perturbative route toward analytical theories of intermittency in turbulence. This is a joint work with Simon Thalabard.
Title: Perturbative anomalous exponents from Kolmogorov multipliers
Speaker: Alexei Maliybaev
Abstract: /span>Intermittency, manifested through anomalous scaling, remains one of the central unresolved problems in turbulence theory, with few analytical approaches extending beyond idealized linear transport models. We introduce a perturbative framework for anomalous scaling in turbulent transport based on multiplier statistics, rather than zero-mode calculations. We demonstrate the approach using a shell model combining deterministic and Kraichnan-like stochastic components. We reduce the problem to the analysis of a stationary Fokker-Planck equation for Kolmogorov multipliers, defined as ratios of successive scalar amplitudes. Its solution yields the invariant measure through a perturbative expansion around a Gaussian distribution. Using the resulting multiplier statistics, we compute explicit anomalous scaling exponents for structure functions of arbitrary order, including odd, even, and non-integer moments. Although demonstrated here for a shell model, the framework suggests a systematic perturbative route toward analytical theories of intermittency in turbulence. This is a joint work with Simon Thalabard.
Friday, September 18th, 2026
Workshop: Luca Biferale
Time: 9:30 AM - 10:30 AM
Location: SCGP 102
Title: Data-driven Modeling of Eulerian and Lagrangian Turbulence
Speaker: Luca Biferale
Abstract: /span>We present different stochastic generative frameworks for the generation and augmentation of complex, multiscale signals arising in Eulerian and Lagrangian turbulence. The approach builds on generative Diffusion Models, a class of probabilistic deep learning methods capable of learning high-dimensional data distributions beyond Gaussian approximations.We demonstrate applications to both three-, two- and one-dimensional stochastic signals, including the temporal evolution of turbulent observables along Lagrangian trajectories. The proposed methodology is benchmarked against Gaussian Process Regression using complementary statistical diagnostics and pointwise error metrics. Particular emphasis is placed on the faithful reproduction of non-Gaussian statistics, intermittency, extreme events, and scale-dependent correlations.We further present preliminary results on the generalization to memorization transition.
Title: Data-driven Modeling of Eulerian and Lagrangian Turbulence
Speaker: Luca Biferale
Abstract: /span>We present different stochastic generative frameworks for the generation and augmentation of complex, multiscale signals arising in Eulerian and Lagrangian turbulence. The approach builds on generative Diffusion Models, a class of probabilistic deep learning methods capable of learning high-dimensional data distributions beyond Gaussian approximations.We demonstrate applications to both three-, two- and one-dimensional stochastic signals, including the temporal evolution of turbulent observables along Lagrangian trajectories. The proposed methodology is benchmarked against Gaussian Process Regression using complementary statistical diagnostics and pointwise error metrics. Particular emphasis is placed on the faithful reproduction of non-Gaussian statistics, intermittency, extreme events, and scale-dependent correlations.We further present preliminary results on the generalization to memorization transition.
Workshop: Guru Jayasingh
Time: 11:00 AM - 12:00 PM
Location: SCGP 102
Title:
Speaker: Guru Jayasingh
Abstract: /span>
Title:
Speaker: Guru Jayasingh
Abstract: /span>
Workshop: Snehanshu Maiti
Time: 1:00 PM - 2:00 PM
Location: SCGP 102
Title: Eulerian–Lagrangian Relations in Decaying Two-Dimensional Navier–Stokes Turbulence
Speaker: Snehanshu Maiti
Abstract: /span>
Title: Eulerian–Lagrangian Relations in Decaying Two-Dimensional Navier–Stokes Turbulence
Speaker: Snehanshu Maiti
Abstract: /span>
Workshop: Daniel Lecoanet
Time: 2:30 PM - 3:30 PM
Location: SCGP 102
Title:
Speaker: Daniel Lecoanet
Abstract: /span>
Title:
Speaker: Daniel Lecoanet
Abstract: /span>