Weakly Nonlinear Instability of a Convective Flow in a Plane Vertical Channel

The weakly nonlinear stability analysis of a convective flow in a planar vertical fluid layer is performed in this paper. The base flow in the vertical direction is generated by internal heat sources distributed within the fluid. The system of Navier–Stokes equations under the Boussinesq approximati...

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Main Authors: Natalja Budkina, Valentina Koliskina, Andrei Kolyshkin, Inta Volodko
Format: Article
Language:English
Published: MDPI AG 2025-04-01
Series:Fluids
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Online Access:https://www.mdpi.com/2311-5521/10/5/111
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author Natalja Budkina
Valentina Koliskina
Andrei Kolyshkin
Inta Volodko
author_facet Natalja Budkina
Valentina Koliskina
Andrei Kolyshkin
Inta Volodko
author_sort Natalja Budkina
collection DOAJ
description The weakly nonlinear stability analysis of a convective flow in a planar vertical fluid layer is performed in this paper. The base flow in the vertical direction is generated by internal heat sources distributed within the fluid. The system of Navier–Stokes equations under the Boussinesq approximation and small-Prandtl-number approximation is transformed to one equation containing a stream function. Linear stability calculations with and without a small-Prandtl-number approximation lead to the range of the Prantdl numbers for which the approximation is valid. The method of multiple scales in the neighborhood of the critical point is used to construct amplitude evolution equation for the most unstable mode. It is shown that the amplitude equation is the complex Ginzburg–Landau equation. The coefficients of the equation are expressed in terms of integrals containing the linear stability characteristics and the solutions of three boundary value problems for ordinary differential equations. The results of numerical calculations are presented. The type of bifurcation (supercritical bifurcation) predicted by weakly nonlinear calculations is in agreement with experimental data.
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spelling doaj-art-bf0154f5773a4e1886806f8aab65225b2025-08-20T03:47:58ZengMDPI AGFluids2311-55212025-04-0110511110.3390/fluids10050111Weakly Nonlinear Instability of a Convective Flow in a Plane Vertical ChannelNatalja Budkina0Valentina Koliskina1Andrei Kolyshkin2Inta Volodko3Institute of Applied Mathematics, Riga Technical University, Zunda Embankment 10, LV 1048 Riga, LatviaInstitute of Applied Mathematics, Riga Technical University, Zunda Embankment 10, LV 1048 Riga, LatviaInstitute of Applied Mathematics, Riga Technical University, Zunda Embankment 10, LV 1048 Riga, LatviaInstitute of Applied Mathematics, Riga Technical University, Zunda Embankment 10, LV 1048 Riga, LatviaThe weakly nonlinear stability analysis of a convective flow in a planar vertical fluid layer is performed in this paper. The base flow in the vertical direction is generated by internal heat sources distributed within the fluid. The system of Navier–Stokes equations under the Boussinesq approximation and small-Prandtl-number approximation is transformed to one equation containing a stream function. Linear stability calculations with and without a small-Prandtl-number approximation lead to the range of the Prantdl numbers for which the approximation is valid. The method of multiple scales in the neighborhood of the critical point is used to construct amplitude evolution equation for the most unstable mode. It is shown that the amplitude equation is the complex Ginzburg–Landau equation. The coefficients of the equation are expressed in terms of integrals containing the linear stability characteristics and the solutions of three boundary value problems for ordinary differential equations. The results of numerical calculations are presented. The type of bifurcation (supercritical bifurcation) predicted by weakly nonlinear calculations is in agreement with experimental data.https://www.mdpi.com/2311-5521/10/5/111weakly nonlinear instabilityconvective flowcollocation method
spellingShingle Natalja Budkina
Valentina Koliskina
Andrei Kolyshkin
Inta Volodko
Weakly Nonlinear Instability of a Convective Flow in a Plane Vertical Channel
Fluids
weakly nonlinear instability
convective flow
collocation method
title Weakly Nonlinear Instability of a Convective Flow in a Plane Vertical Channel
title_full Weakly Nonlinear Instability of a Convective Flow in a Plane Vertical Channel
title_fullStr Weakly Nonlinear Instability of a Convective Flow in a Plane Vertical Channel
title_full_unstemmed Weakly Nonlinear Instability of a Convective Flow in a Plane Vertical Channel
title_short Weakly Nonlinear Instability of a Convective Flow in a Plane Vertical Channel
title_sort weakly nonlinear instability of a convective flow in a plane vertical channel
topic weakly nonlinear instability
convective flow
collocation method
url https://www.mdpi.com/2311-5521/10/5/111
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AT valentinakoliskina weaklynonlinearinstabilityofaconvectiveflowinaplaneverticalchannel
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AT intavolodko weaklynonlinearinstabilityofaconvectiveflowinaplaneverticalchannel