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Updated: Jun 22, 2026
06:07
Studying Large Amplitude Oscillatory Shear Response of Soft Materials
Published on: April 25, 2019
Extended fluctuation-dissipation theorem for soft matter in stationary flow
1II. Institut für Theoretische Physik, Universität Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart, Germany.
Summary
We present an extended fluctuation-dissipation theorem (FDT) for soft matter under flow. This new FDT accounts for nonlinear effects and extends Onsager
Area of Science:
- Soft Matter Physics
- Non-equilibrium Statistical Mechanics
Background:
- Traditional fluctuation-dissipation theorem (FDT) applies to systems in equilibrium or near-equilibrium.
- Soft matter systems driven by stationary flow often operate far from equilibrium.
Purpose of the Study:
- To develop an extended FDT applicable to soft matter systems under strong stationary flow.
- To investigate nonlinear effects beyond the linear-response regime.
Main Methods:
- Analytical evaluation for Rouse polymers.
- Numerical simulations for colloidal suspensions.
Main Results:
- The FDT for stress gains an additional term involving the observable conjugate to the strain rate.
- The extended FDT is validated in both analytical and numerical models.
- Demonstrated applicability to Rouse polymers and colloidal suspensions.
Conclusions:
- The study proposes an extended FDT for non-equilibrium steady states in soft matter.
- The findings suggest a generalization of Onsager's regression principle to these systems.
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