arXiv subjects

V. Karlin

Publications and source records attributed to V. Karlin.

4 recordsLinked to original sources

arXiv2009

Global communications in multiprocessor simulations of flames

In this paper we investigate performance of global communications in a particular parallel code. The code simulates dynamics of expansion of premixed spherical flames using an asymptotic model of Sivashinsky type and a spectral numerical algorithm. As a result, the code heavily relies on global all-to-all interprocessor communications implementing transposition of the distributed data array in which numerical solution to the problem is stored. This global data interdependence makes interprocessor connectivity of the HPC system as important as the floating-point power of the processors of which the system is built. Our experiments show that efficient numerical simulation of this particular model, with global data interdependence, on modern HPC systems is possible. Prospects of performance of more sophisticated models of flame dynamics are analysed as well.

cs.DC↗

arXiv2005

The Rate of Expansion of Spherical Flames

In this paper we investigate the acceleration of the expansion of premixed spherical flames and evolution of the cellular patterns on their surfaces. An asymptotic model is used for the simulations and a spectral numerical algorithm is employed to study flames over large time intervals. Numerous numerical experiments indicate that for large enough time intervals the acceleration of two-dimensional expanding flame ceases and the expansion rate stabilizes to a value significantly exceeding the burning rate. The importance of the effect of forcing was also confirmed and the validity of sectorial simulations of closed flames was studied in order to justify prospective use of the Fourier spectral model for the three-dimensional spherical flames.

physics.flu-dyn↗

arXiv2005

Detailed analysis of a pseudoresonant interaction between cellular flames and velocity turbulence

This work is dedicated to the analysis of the delicate details of the effect of upstream velocity fluctuations on the flame propagation speed. The investigation was carried out using the Sivashinsky model of cellularisation of hydrodynamically unstable flame fronts. We identified the perturbations of the steadily propagating flames which can be significantly amplified over finite periods of time. These perturbations were used to model the effect of upstream velocity fluctuations on the flame front dynamics and to study a possibility to control the flame propagation speed.

physics.flu-dyn↗

arXiv2003

Estimation of the linear transient growth of perturbations of cellular flames

In this work we estimate rates of the linear transient growth of the perturbations of cellular flames governed by the Sivashinsky equation. The possibility and significance of such a growth was indicated ear- lier in both computational and analytical investigations. Numerical investigation of the norm of the resolvent of the linear operator asso- ciated with the Sivashinsky equation linearized in a neighbourhood of the steady coalescent pole solution was undertaken. The results are presented in the form of the pseudospectra and the lower bound of possible transient amplification. This amplification is strong enough to make the round-off errors visible in the numerical simulations in the form of small cusps appearing on the flame surface randomly in time. Performance of available numerical approaches was compared to each other and the results are checked versus directly calculated norms of the evolution operator.

physics.flu-dyn↗