1,721,318 research outputs found
A new mechanism for buoyancy driven convection in pulsating viscous flows: A theoretical study
No full textA new mechanism for the onset of thermal convection is proposed. This mechanism is the result of the interaction between a pulsating flow, viscous dissipation, and buoyancy within a channel. The study considers a Newtonian fluid moving inside an infinitely wide horizontal channel bounded by impermeable, rigid plates. The basic flow is characterized by a pulsating pressure gradient. Viscous dissipation acts as an internal heat source which produces a potentially unstable basic temperature gradient. The heat source has a vertical non uniform distribution inside the channel. This configuration is investigated with respect to the onset of buoyancy driven convection. The basic state fields are solved analytically by expanding them in series as functions of the pulsating frequency. In order to perform the linear stability analysis, an arbitrarily small perturbation is superimposed upon the basic state order zero solution. The normal mode method is employed and an ordinary differential eigenvalue problem is obtained. The perturbations were found to have zero angular frequency and thus the resonance phenomena between the basic flow and the perturbations can be neglected. The critical values of the governing parameter are obtained by solving the eigenvalue problem numerically. A growth rate analysis of the possibly unstable configurations relative to the most unstable mode is performed. The present study proves, theoretically, that a pulsating flow can undergo thermal convection. A future experimental study is suggested to validate the proposed instability mechanism
A new hydrodynamic boundary condition simulating the effect of rough boundaries on the onset of Rayleigh-Bénard convection
No full textThis paper introduces a new hydrodynamic boundary condition which enables the simulation of the effects caused by rough boundaries. The classical Rayleigh-Bénard stability analysis is performed here to investigate the onset of thermal convection in a parallel-plate channel with rough boundaries. The hydrodynamic boundary conditions are modified, from the classical treatment, in order to consider channel boundaries characterised by non-negligible roughness. This roughness is simulated as a shallow fluid saturated porous medium and the Saffman interface condition is thus employed to model the hydrodynamic boundary conditions. The normal mode method is employed and the obtained eigenvalue problem is solved numerically. The Principle of Exchange of Stabilities is proved and the critical values of the Rayleigh number and of the wave number are obtained
Thismia mucronata (Thismiaceae), a new species from Southern Vietnam
No full textNuraliev, Maxim S., Beer, Anton S., Kuznetsov, Andrey N., Kuznetsova, Svetlana P. (2014): Thismia mucronata (Thismiaceae), a new species from Southern Vietnam. Phytotaxa 167 (3): 245-255, DOI: 10.11646/phytotaxa.167.3.3, URL: http://dx.doi.org/10.11646/phytotaxa.167.3.
Citronella suaveolens, a new generic record for Vietnam, with a key to Vietnamese Cardiopteridaceae
No full textNuraliev, Maxim S., Schori, Melanie, Tagane, Shuichiro, Kuznetsov, Andrey N., Kuznetsova, Svetlana P., Utteridge, Timothy M.A. (2022): Citronella suaveolens, a new generic record for Vietnam, with a key to Vietnamese Cardiopteridaceae. Phytotaxa 532 (1): 67-77, DOI: 10.11646/phytotaxa.532.1.
FIGURE 4. Thismia angustimitra. A in Thismia mucronata (Thismiaceae), a new species from Southern Vietnam
No full textFIGURE 4. Thismia angustimitra. A. Plants in natural habitat. B. Flowers. All photos by P.Tripetch.Published as part of Nuraliev, Maxim S., Beer, Anton S., Kuznetsov, Andrey N. & Kuznetsova, Svetlana P., 2014, Thismia mucronata (Thismiaceae), a new species from Southern Vietnam, pp. 245-255 in Phytotaxa 167 (3) on page 251, DOI: 10.11646/phytotaxa.167.3.3, http://zenodo.org/record/513881
Tupistra khangii (Asparagaceae), a new species from northern Vietnam
No full textVislobokov, Nikolay A., Тanaka, Noriyuki, Averyanov, Leonid V., Nguyen, Hiep Tien, Nuraliev, Maxim S., Kuznetsov, Andrey N. (2014): Tupistra khangii (Asparagaceae), a new species from northern Vietnam. Phytotaxa 175 (5): 287-292, DOI: 10.11646/phytotaxa.175.5.8, URL: http://dx.doi.org/10.11646/phytotaxa.175.5.
Untangling the taxonomy of Phlogacanthus pulcherrimus (Acanthaceae) newly recorded from Vietnam
No full textHai, Do Van, Hoan, Duong Thi, Nuraliev, Maxim S., Kuznetsov, Andrey N., Kuznetsova, Svetlana P., Choudhary, Ritesh Kumar, Lee, Joongku (2021): Untangling the taxonomy of Phlogacanthus pulcherrimus (Acanthaceae) newly recorded from Vietnam. Phytotaxa 518 (1): 45-53, DOI: 10.11646/phytotaxa.518.1.
FIGURE 2. Ardisia patentiradiosa. A in Ardisia patentiradiosa (Primulaceae), a new species from southern Vietnam
No full textFIGURE 2. Ardisia patentiradiosa. A. flowering branch; B. inflorescence; C. abaxial leaf surface; D–E. flowers; F. dorsal view of a flower showing calyx.Published as part of Nuraliev, Maxim S., Kuznetsov, Andrey N., Kuznetsova, Svetlana P. & Hu, Chi-Ming, 2021, Ardisia patentiradiosa (Primulaceae), a new species from southern Vietnam, pp. 63-67 in Phytotaxa 522 (1) on page 65, DOI: 10.11646/phytotaxa.522.1.7, http://zenodo.org/record/554905
Didymoplexis gibbosa (Orchidaceae), a new mycoheterotrophic species from southern Vietnam
No full textAveryanov, Leonid V., Maisak, Tatiana V., Lyskov, Dmitry F., Kuznetsov, Andrey N., Kuznetsova, Svetlana P., Nuraliev, Maxim S. (2022): Didymoplexis gibbosa (Orchidaceae), a new mycoheterotrophic species from southern Vietnam. Phytotaxa 556 (2): 207-212, DOI: 10.11646/phytotaxa.556.2.11, URL: http://dx.doi.org/10.11646/phytotaxa.556.2.1
Leptomischus multiflorus (Argostemmateae: Rubiaceae), a new species from southern Vietnam
No full textNuraliev, Maxim S., Nguyen, Khang Sinh, Pham, Thoa Kim Thi, Nguyen, Cuong Huu, Quang, Bui Hong, Lyskov, Dmitry F., Kuznetsov, Andrey N., Kuznetsova, Svetlana P., Wu, Lei (2022): Leptomischus multiflorus (Argostemmateae: Rubiaceae), a new species from southern Vietnam. Phytotaxa 574 (1): 83-90, DOI: 10.11646/phytotaxa.574.1.5, URL: http://dx.doi.org/10.11646/phytotaxa.574.1.
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