210 citations · 1.3k across the 48 of their papers we have counts for
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Spontaneous Symmetry Breaking for Extreme Vorticity and Strain in the 3D Navier-Stokes Equations
Timo Schorlepp, Tobias Grafke, Sandra May +1
We investigate the spatio-temporal structure of the most likely configurations realising extremely high vorticity or strain in the stochastically forced 3D incompressible Navier-St…
Explicit construction of joint multipoint statistics in complex systems
J. Friedrich, J. Peinke, A. Pumir +1
Complex systems often involve random fluctuations for which self-similar properties in space and time play an important role. Fractional Brownian motions, characterized by a single…
Multi-level stochastic refinement for complex time series and fields: A Data-Driven Approach
M. Sinhuber, J. Friedrich, R. Grauer +1
Spatio-temporally extended nonlinear systems often exhibit a remarkable complexity in space and time. In many cases, extensive datasets of such systems are difficult to obtain, yet…
Multiscale velocity correlations in turbulence and Burgers turbulence: Fusion rules, Markov processes in scale, and multifractal predictions
Jan Friedrich, Georgios Margazoglou, Luca Biferale +1
We compare different approaches towards an effective description of multi-scale velocity field correlations in turbulence. Predictions made by the operator product expansion, the s…
Dynamo enhancement and mode selection triggered by high magnetic permeability
Sophia Kreuzahler, Yannick Ponty, Nicolas Plihon +2
We present results from consistent dynamo simulations, where the electrically conducting and incompressible flow inside a cylinder vessel is forced by moving impellers numerically…
Generalized description of intermittency in turbulence via stochastic methods
J. Friedrich, R. Grauer
We present a generalized picture of intermittency in turbulence that is based on the theory of stochastic processes. To this end, we rely on the experimentally and numerically veri…
Longitudinal and transverse structure functions in high Reynolds-number magneto-hydrodynamic turbulence
J. Friedrich, H. Homann, T. Schäfer +1
We investigate the scaling behavior of longitudinal and transverse structure functions in homogeneous and isotropic magneto-hydrodynamic (MHD) turbulence by means of an exact hiera…
The instanton method and its numerical implementation in fluid mechanics
Tobias Grafke, Rainer Grauer, Tobias Schäfer
A precise characterization of structures occurring in turbulent fluid flows at high Reynolds numbers is one of the last open problems of classical physics. In this review we discus…
Irreversibility and small-scale generation in 3D turbulent flows
Alain Pumir, Haitao Xu, Rainer Grauer +1
In three-dimensional turbulent flows energy is supplied at large scales and cascades down to the smallest scales where viscosity dominates. The flux of energy through scales implie…
Efficient Computation of Instantons for Multi-Dimensional Turbulent Flows with Large Scale Forcing
Tobias Grafke, Rainer Grauer, Stephan Schindel
Extreme events play a crucial role in fluid turbulence. Inspired by methods from field theory, these extreme events, their evolution and probability can be computed with help of th…
Lagrangian and geometric analysis of finite-time Euler singularities
Tobias Grafke, Rainer Grauer
We present a numerical method of analyzing possibly singular incompressible 3D Euler flows using massively parallel high-resolution adaptively refined numerical simulations up to 8…
Finite-Time Euler singularities: A Lagrangian perspective
Tobias Grafke, Rainer Grauer
We address the question whether a singularity in a three-dimensional incompressible inviscid fluid flow can occur in finite time. Analytical considerations and numerical simulation…
Instanton filtering for the stochastic Burgers equation
Tobias Grafke, Rainer Grauer, Tobias Schäfer
We address the question whether one can identify instantons in direct numerical simulations of the stochastically driven Burgers equation. For this purpose, we first solve the inst…
Turbulence properties and global regularity of a modified Navier-Stokes equation
Tobias Grafke, Rainer Grauer, Thomas C. Sideris
We introduce a modification of the Navier-Stokes equation that has the remarkable property of possessing an infinite number of conserved quantities in the inviscid limit. This new…
Effect of turbulent fluctuations on the drag and lift forces on a towed sphere and its boundary layer
Holger Homann, Jérémie Bec, Rainer Grauer
The impact of turbulent fluctuations on the forces exerted by a fluid on a towed spherical particle is investigated by means of high-resolution direct numerical simulations. The me…
Longitudinal and Transverse structure functions in high Reynolds-number turbulence
Rainer Grauer, Holger Homann, Jean-Francois Pinton
Using exact relations between velocity structure functions (Hill, Hill and Boratav, and Yakhot) and neglecting pressure contributions in a first approximation, we obtain a closed s…
Conditional Eulerian and Lagrangian velocity increment statistics of fully developed turbulent flow
Holger Homann, Daniel Schulz, Rainer Grauer
Conditional statistics of homogeneous isotropic turbulent flow is investigated by means of high-Reynolds number direct numerical simulations performed with collocation poi…
Numerical simulations of possible finite time singularities in the incompressible Euler equations: comparison of numerical methods
Tobias Grafke, Holger Homann, Juergen Dreher +1
The numerical simulation of the 3D incompressible Euler equation is analyzed with respect to different integration methods. The numerical schemes we considered include spectral met…
Density-PDFs and Lagrangian Statistics of highly compressible Turbulence
Christoph Beetz, Christian Schwarz, Jürgen Dreher +1
We report on probability-density-functions (PDF) of the mass density in numerical simulations of highly compressible hydrodynamic flows and the corresponding structure formation of…
A Corrsin type approximation for Lagrangian fluid Turbulence
Rudolf Friedrich, Rainer Grauer, Holger Homann +1
In Lagrangian turbulence one is faced with the puzzle that 2D Navier-Stokes flows are nearly as intermittent as in three dimensions although no intermittency is present in the inve…