arXiv subjects

Manohar Teja Kalluri

Publications and source records attributed to Manohar Teja Kalluri.

4 recordsLinked to original sources

arXiv2025

Comparing the magnetic Rayleigh-Taylor instability dynamics in two- and three-dimensions

The magnetic Rayleigh-Taylor instability (MRTI) governs plasma mixing and transport in a wide range of astrophysical and laboratory systems. Owing to computational constraints, MRTI is often studied using two-dimensional (2D) simulations, but the extent to which 2D captures the true three-dimensional (3D) dynamics remains unclear. In this work, we perform direct numerical simulations of non-ideal, incompressible MRTI in both 2D and 3D, systematically varying the magnetic field strength from weakly to strongly magnetized regimes. We find that the 3D system exhibits richer mode interactions due to the coexistence of interchange, undular, and mixed modes structures that are inherently absent in 2D. The mixing layer in 3D has enhanced small-scale mixing and reduced fluid dispersion compared to 2D, which is characterized by large-scale plumes. Energy diagnostics reveal that the gravitational potential energy released is higher in 2D, primarily because of inefficient mixing and significant fluid dispersion. In contrast, 3D systems display greater energy dissipation and anisotropy, driven by small-scale vortical motions. The non-linear growth of the instability increases monotonically with magnetic field strength in 3D but shows a non-monotonic trend in 2D. Despite these broad differences, the rate of magnetic-to-kinetic energy conversion remains remarkably similar across dimensions, indicating that 2D simulations can meaningfully capture reconnection-driven processes but not the full turbulent evolution. Overall, our results demonstrate that 2D MRTI simulations cannot reliably represent 3D mixing, energy dynamics, or nonlinear growth, highlighting the fundamental importance of three-dimensionality in magnetized plasma instabilities.

physics.flu-dyn↗

arXiv2025

Quantifying Reconnection and it's Dynamical Role in 2D Magnetic Rayleigh-Taylor Turbulence

Magnetic Rayleigh-Taylor instability (MRTI) governs material transport and mixing in astrophysical and laboratory plasmas under the influence of gravity and magnetic fields. While magnetic reconnection is known to occur during MRTI evolution, its role in the evolution and energy dynamics remains poorly understood. Here, we present a comprehensive analysis of the role of reconnection in the two-dimensional MRTI dynamics, using high-resolution simulations. We establish that reconnection, through facilitating plume merger, relieving magnetic tension, and enabling continued instability growth, forms an essential component for the long-term instability evolution. To quantify the role of reconnection in energy dynamics, we develop a robust automated reconnection detection algorithm and perform a statistical analysis across a range of magnetic field strengths. We find that reconnection accounts for up to $80\%$ of the magnetic-to-kinetic energy transfer in the weak magnetic field regime, while contributing minimally ($\approx 3\%$) to magnetic energy dissipation. Our results establish magnetic reconnection as a critical mechanism that regulates large-scale MRTI dynamics, with implications for astrophysical plasmas and turbulent mixing in magnetized flows.

physics.plasm-ph↗

arXiv2025

Self-similarity and growth of non-linear magnetic Rayleigh-Taylor instability -- Role of the magnetic field strength

The non-linear regime of the magnetic Rayleigh-Taylor instability (MRTI) has been studied in the context of several laboratory and astrophysical systems. Yet, several fundamental aspects remain unclear. One of them is the self-similar evolution of the instability. Studies have assumed that non-linear MRTI has a self-similar, quadratic growth similar to hydrodynamic (HD) RTI. However, neither self-similarity nor quadratic growth has been proved analytically. Furthermore, an explicit understanding of the factors that control the growth of non-linear instability remains unclear. Magnetic fields are known to play a crucial role in the evolution of the instability. Yet, a systematic study discussing how the magnetic field influences the instability growth is missing. These issues were addressed by performing an analytical and numerical study of the MRTI with a uniform magnetic field. Our study reveals that the imposed magnetic field does not conform to the HD self-similar evolution. However, the influence of the imposed magnetic field decays with time (t) as 1/t relative to the other non-linear terms, making the MRTI conform to the HD self-similarity. Thus, the HD RTI self-similar scaling becomes relevant to MRTI at late times, when nonlinear dynamics dominate. Based on energy conservation, an equation for the mixing layer height (h) is derived, which demonstrates the quadratic growth of h in time. This gave insight into various factors that could influence the non-linear growth of the instability. By studying MRTI at different magnetic field strengths, we demonstrate the role of magnetic field strength on the nonlinear growth of MRTI. Thus, the current study analytically and numerically proves the role of magnetic fields on the evolution of MRTI.

physics.flu-dyn↗

arXiv2022

Shear-layer dynamics at the interface of parallel Couette flows

This article aims to make a detailed analysis of co-flowing plane Couette flows. Particularly, the variation of flow quantities from the turbulent to non-turbulent region is studied. While the enstrophy exhibits a sharp jump, the other quantities (e.g., mean velocity, Reynolds normal stress, and kinetic energy) show a continuous variation across the interface. The budget analysis of Reynolds normal stresses reveals that the terms playing a key role in turbulence transportation vary depending on the Reynolds normal stress under study. The terms production, diffusion, and redistribution play an important role in streamwise Reynolds stress ðu0u0 Þ. In the spanwise Reynolds stress ðv0v0 Þ, the diffusion terms play a significant role. In the wall-normal Reynolds stress ðw0w0 Þ, only the redistribution term is significant. The influence of one flow over another in the co-flow state was observed through the additional mean velocity and Reynolds normal stress found in the system compared to a standard plane Couette flow (pCf). Comparing the co-flow system with a conventional pCf system, the former exhibits greater vorticity, vortex stretching, and kinetic energy. A detailed analysis on the geometry and topology of flow structures was studied using flow invariants.

physics.flu-dyn↗