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The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material.Thu, 30 Nov 2023 18:18:02 GMT2023-11-30T18:18:02ZStability of thermocapillary flow in liquid bridges fully coupled to the gas phase
http://hdl.handle.net/10985/24324
Stability of thermocapillary flow in liquid bridges fully coupled to the gas phase
STOJANOVIĆ, Mario; ROMANO, Francesco; KUHLMANN, Hendrik C.
The linear stability of the axisymmetric steady thermocapillary flow in a liquid bridge made from 2 cSt silicone oil (Prandtl number 28) is investigated numerically in the framework of the Boussinesq approximation. The flow and temperature fields in the surrounding gas phase (air) are taken into account for a generic cylindrical container hosting the liquid bridge. The flows in the liquid and in the gas are fully coupled across the hydrostatically deformed liquid–gas interface, neglecting dynamic interface deformations. Originating from a common reference case, the linear stability boundary is computed varying the length of the liquid bridge (aspect ratio), its volume and the gravity level, providing accurate critical data. The qualitative dependence of the critical threshold on these parameters is explained in terms of the characteristics of the critical mode. The heat exchange between the ambient gas and the liquid bridge that is fully resolved has an important influence on the critical conditions.
Thu, 01 Sep 2022 00:00:00 GMThttp://hdl.handle.net/10985/243242022-09-01T00:00:00ZSTOJANOVIĆ, MarioROMANO, FrancescoKUHLMANN, Hendrik C.The linear stability of the axisymmetric steady thermocapillary flow in a liquid bridge made from 2 cSt silicone oil (Prandtl number 28) is investigated numerically in the framework of the Boussinesq approximation. The flow and temperature fields in the surrounding gas phase (air) are taken into account for a generic cylindrical container hosting the liquid bridge. The flows in the liquid and in the gas are fully coupled across the hydrostatically deformed liquid–gas interface, neglecting dynamic interface deformations. Originating from a common reference case, the linear stability boundary is computed varying the length of the liquid bridge (aspect ratio), its volume and the gravity level, providing accurate critical data. The qualitative dependence of the critical threshold on these parameters is explained in terms of the characteristics of the critical mode. The heat exchange between the ambient gas and the liquid bridge that is fully resolved has an important influence on the critical conditions.Instability of axisymmetric flow in thermocapillary liquid bridges: Kinetic and thermal energy budgets for two-phase flow with temperature-dependent material properties
http://hdl.handle.net/10985/24482
Instability of axisymmetric flow in thermocapillary liquid bridges: Kinetic and thermal energy budgets for two-phase flow with temperature-dependent material properties
STOJANOVIĆ, Mario; ROMANO, Francesco; KUHLMANN, Hendrik C.
In numerical linear stability investigations, the rates of change of the kinetic and thermal energy of the perturbation flow are often used to identify the dominant mechanisms by which kinetic or thermal energy is exchanged between the basic and the perturbation flow. Extending the conventional energy analysis for a single-phase Boussinesq fluid, the energy budgets of arbitrary infinitesimal perturbations to the basic two-phase liquid–gas flow are derived for an axisymmetric thermocapillary bridge when the material parameters in both phases depend on the temperature. This allows identifying individual transport terms and assessing their contributions to the instability if the basic flow and the critical mode are evaluated at criticality. The full closed-form energy budgets of linear modes have been derived for thermocapillary two-phase flow taking into account the temperature dependence of all thermophysical parameters. The influence of different approximations to the temperature dependence on the linear stability boundary of the axisymmetric flow in thermocapillary liquid bridges is tested regarding their accuracy. The general mechanism of symmetry breaking turns out to be very robust.
Sat, 01 Jul 2023 00:00:00 GMThttp://hdl.handle.net/10985/244822023-07-01T00:00:00ZSTOJANOVIĆ, MarioROMANO, FrancescoKUHLMANN, Hendrik C.In numerical linear stability investigations, the rates of change of the kinetic and thermal energy of the perturbation flow are often used to identify the dominant mechanisms by which kinetic or thermal energy is exchanged between the basic and the perturbation flow. Extending the conventional energy analysis for a single-phase Boussinesq fluid, the energy budgets of arbitrary infinitesimal perturbations to the basic two-phase liquid–gas flow are derived for an axisymmetric thermocapillary bridge when the material parameters in both phases depend on the temperature. This allows identifying individual transport terms and assessing their contributions to the instability if the basic flow and the critical mode are evaluated at criticality. The full closed-form energy budgets of linear modes have been derived for thermocapillary two-phase flow taking into account the temperature dependence of all thermophysical parameters. The influence of different approximations to the temperature dependence on the linear stability boundary of the axisymmetric flow in thermocapillary liquid bridges is tested regarding their accuracy. The general mechanism of symmetry breaking turns out to be very robust.MaranStable: A linear stability solver for multiphase flows in canonical geometries
http://hdl.handle.net/10985/24504
MaranStable: A linear stability solver for multiphase flows in canonical geometries
STOJANOVIĆ, Mario; ROMANO, Francesco; KUHLMANN, Hendrik C.
MaranStable is a software to perform three-dimensional linear stability analyses of steady two-dimensional non-isothermal multiphase flows in canonical geometries. Different approximations to the Navier–Stokes equations can be selected, which are discretized by finite volumes on a staggered grid. The stability of the basic flow, obtained by Newton—Raphson iteration, is computed by solving the linearized three-dimensional perturbation equations using normal modes. All calculations are based on Matlab and make extensive use of the already parallelized backslash and eigs operators, and the graphical user interface eases the access to MaranStable.
Sat, 01 Jul 2023 00:00:00 GMThttp://hdl.handle.net/10985/245042023-07-01T00:00:00ZSTOJANOVIĆ, MarioROMANO, FrancescoKUHLMANN, Hendrik C.MaranStable is a software to perform three-dimensional linear stability analyses of steady two-dimensional non-isothermal multiphase flows in canonical geometries. Different approximations to the Navier–Stokes equations can be selected, which are discretized by finite volumes on a staggered grid. The stability of the basic flow, obtained by Newton—Raphson iteration, is computed by solving the linearized three-dimensional perturbation equations using normal modes. All calculations are based on Matlab and make extensive use of the already parallelized backslash and eigs operators, and the graphical user interface eases the access to MaranStable.