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Kamen N Beronov

Publications and source records attributed to Kamen N Beronov.

2 recordsLinked to original sources

[Numerical simulations of pulsating flow in intracranial blood vessels with aneurysms using Lattice Boltzmann methods].

A major prerequisite for successful planning and control of the medical treatment of blood vessels with stenoses or aneurysms is the detailed knowledge of the individual situation in the damaged vessels. Modern tomography methods provide good spatial resolution, so that vessel walls as well as prostheses can be easily and rapidly identified. However, the mechanical loads of the walls remain largely unknown. In the past few years, tomography data have been used for spatial and temporal simulations of the blood flow in such vessels and to predict the mechanical loads of the vessel walls. The methodologies used so far, however, involve elaborate grid generation and simulation steps, most often relying on commercial software suited for engineering projects. These require specific knowledge and experience in mechanics and numerical simulation, and are therefore inappropriate for clinical applications. It is now shown, by example of an intracranial aneurysm, that employing a Lattice Boltzmann method for the flow simulation allows to avoid all mentioned drawbacks and to simulate blood flows in a fast and simple way that is also appropriate for clinical use. The practical relevance of such simulations will be enhanced by a better understanding of the correlations between pathology and specific mechanical loads. The paper discusses also some aspects of fluid mechanics that are relevant for the study of aneurysms.

Blood Flow Velocity↗

Second-order structure function scaling derivation from the Euler and magnetohydrodynamic equations.

An anomalous scaling paradigm that has recently come to be canonical has two features limiting its range of applicability: The driving and driven fields are separated dyamically and the driving field statistics is prescribed, in terms of the (inertial subrange) scaling of its second-order structure functions and of white-noise statistics in time. Then the spectrum of scaling exponents for the driven field, scalar or vector, depends parametrically on the driving. Here, the coupling of turbulent vorticity to the driving velocity field is considered. Using simple approximations and no white-noise statistics assumption, equations are derived for the evolution of two-point second-order correlations. The turbulent magnetohydrodynamic (MHD) case is treated in an analogous fashion. In the neutral case, the kinematic coupling between vorticity and velocity leads to a unique prediction for the scaling exponent of the second-order structure functions of the two turbulent fields. The velocity scaling exponent estimate is zeta(2)=3(1/2)-1 approximately equal to 0.732, i.e., close to experimental data. Unlike Kolmogorov scaling, this result is systematically derived from the Euler equations. The analogous scaling of MHD fields is now treated beyond the dynamo theory approximation. In contrast to the uniqueness found in the neutral case, predicted MHD scalings depend on one parameter, similar to the "plasma beta" parameter beta(T) relating kinetic to magnetic energy. The nature of predicted dependence of inertial-range scaling exponents on beta(T) agrees with an observed dichotomy between high-beta(T) and low-beta(T) turbulence regimes.

Journal Article↗