Magneto-Hydrodynamic Squeeze Film Lubrication Mechanics
Summary
Magneto-Hydrodynamic (MHD) squeeze film lubrication describes the behaviour of a thin fluid layer confined between two approaching or oscillating surfaces under the influence of an external magnetic field. In such bearings or interfaces, the classical Reynolds equation is modified to incorporate Lorentz forces arising from interaction between induced currents and the magnetic flux. These electromagnetic body forces can be tuned via the Hartmann number, thereby altering pressure distribution, load-carrying capacity and squeeze-film response time. In parallel, non-Newtonian effects—embodied in couple stress and micropolar fluid models—capture the influence of suspended micro-additives or internal microrotations on shear resistance. Viscosity variation, whether driven by pressure or temperature, further enriches the film dynamics, while stochastic treatments of surface roughness (radial and azimuthal patterns) reveal how micro-scale topography modulates mean film pressure and load support. By integrating these elements, MHD squeeze film studies inform the design of next-generation bearings, dampers and MEMS devices, offering active control of friction, enhanced energy efficiency and prolonged operational life in automotive, aerospace and precision-engineering applications.
Research from Nature Portfolio
Recent studies have developed a unified model that couples couple-stress rheology and spatially varying viscosity with transverse magnetic fields in a squeeze film between a rough flat plate and a curved circular counterpart. Surface roughness is represented by two one-dimensional stochastic patterns—radial and azimuthal—yielding closed-form expressions for mean pressure, load-carrying capacity and squeeze-film time. Numerical analysis demonstrates that an azimuthal roughness pattern significantly boosts film pressure and load support, whereas radial roughness diminishes performance. Moreover, increasing the Hartmann number and the couple-stress parameter leads to stronger Lorentz forces and microstructural resistance, respectively, both of which enhance the film’s outcome relative to classical Newtonian, non-magnetic cases.
Magneto-Hydrodynamic Squeeze Film Lubrication Mechanics publication trend
The graph below shows the total number of articles in magneto-hydrodynamic squeeze film lubrication mechanics across all publications each year (not limited to Nature Index journals).
Technical terms
Magneto-Hydrodynamics (MHD): Study of fluid flow under the influence of magnetic fields, particularly the coupling of Lorentz forces and hydrodynamic behaviour.
Squeeze Film Lubrication: Thin-film lubrication regime in which two surfaces move towards or apart from each other, generating pressure within a confined fluid layer.
Reynolds Equation: Governing equation for thin-film lubrication, modified here to include electromagnetic body forces and non-Newtonian stresses.
Hartmann Number: Dimensionless parameter quantifying the ratio of magnetic to viscous forces in MHD flows.
Couple Stress Fluid: Non-Newtonian fluid model accounting for internal microstructure and rotational stresses within the lubricant.
Micropolar Fluid: Continuum model that incorporates microrotation and microinertia effects of fluid elements.
Viscosity Variation: Dependence of fluid viscosity on pressure or temperature, affecting shear resistance and film thickness.
Piezo-Viscous Dependency: Specific form of viscosity variation where viscosity changes exponentially with pressure.
Stochastic Roughness: Statistical representation of surface irregularities, typically classified into radial and azimuthal patterns for lubrication analysis.
References
- Magnetohydrodynamics and viscosity variation in couple stress squeeze film lubrication between rough flat and curved circular plates. Scientific Reports (2023).
- Combined effect of magneto hydrodynamics, couple stress, and viscosity variation on squeeze film characteristics of a cylinder and rough flat plate. Discover Applied Sciences (2023).
- Magnetohydrodynamic squeeze film characteristics of micropolar fluids with piezo-viscous dependency between wide parallel rectangular plates. Multiscale and Multidisciplinary Modeling, Experiments and Design (2024).
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