scholarly journals Electrostatically controlled surface boundary conditions in nematic liquid crystals and colloids

2019 ◽  
Vol 5 (9) ◽  
pp. eaax4257 ◽  
Author(s):  
Haridas Mundoor ◽  
Bohdan Senyuk ◽  
Mahmoud Almansouri ◽  
Sungoh Park ◽  
Blaise Fleury ◽  
...  
Keyword(s):  
Liquid Crystals ◽  
Boundary Conditions ◽  
Electrostatic Interactions ◽  
Surface Boundary ◽  
Anisotropic Particles ◽  
Surface Alignment ◽  
Surface Charging ◽  
Surface Boundary Conditions ◽  
Anisotropic Elastic ◽  
Colloidal Inclusions

Differing from isotropic fluids, liquid crystals exhibit highly anisotropic interactions with surfaces, which define boundary conditions for the alignment of constituent rod-like molecules at interfaces with colloidal inclusions and confining substrates. We show that surface alignment of the nematic molecules can be controlled by harnessing the competing aligning effects of surface functionalization and electric field arising from surface charging and bulk counterions. The control of ionic content in the bulk and at surfaces allows for tuning orientations of shape-anisotropic particles like platelets within an aligned nematic host and for changing the orientation of director relative to confining substrates. The ensuing anisotropic elastic and electrostatic interactions enable colloidal crystals with reconfigurable symmetries and orientations of inclusions.

Modeling Active Layer Depth of Permafrost Changing Surface Boundary Conditions

2020 ◽  
Author(s):  
MODI ZHU ◽  
Jingfeng Wang ◽  
Husayn Sharif ◽  
Valeriy Ivanov ◽  
Aleksey Sheshukov
Keyword(s):  
Boundary Conditions ◽  
Active Layer ◽  
Surface Boundary ◽  
Layer Depth ◽  
Surface Boundary Conditions

scholarly journals Energy Pile Field Simulation in Large Buildings: Validation of Surface Boundary Assumptions

2019 ◽  
Author(s):  
Andrea Ferrantelli ◽  
Jevgeni Fadejev ◽  
Jarek Kurnitski
Keyword(s):  
Boundary Conditions ◽  
Single Point ◽  
Ground Surface ◽  
Thermal Mass ◽  
Heat Equations ◽  
Outlet Temperature ◽  
Surface Boundary ◽  
Geothermal Heat ◽  
Soil Medium ◽  
Surface Boundary Conditions

As the energy efficiency demands for future buildings become increasingly stringent, preliminary assessments of energy consumption are mandatory. These are possible only through numerical simulations, whose reliability crucially depends on boundary conditions. We therefore investigate their role in numerical estimates for the usage of geothermal energy, performing annual simulations of transient heat transfer for a building employing a geothermal heat pump plant and energy piles. Starting from actual measurements, we solve the heat equations in 2D and 3D using COMSOL Multiphysics and IDA-ICE, and discover a negligible impact of the multiregional ground surface boundary conditions. Moreover, we verify that the thermal mass of the soil medium induces a small vertical temperature gradient on the piles surface. We also find a roughly constant temperature on each horizontal cross-section, with nearly identical values if the average temperature is integrated over the full plane or evaluated at one single point. Calculating the yearly heating need for an entire building we then show that the chosen upper boundary condition affects the energy balance dramatically. Using directly the pipes’ outlet temperature induces a 54% overestimation of the heat flux, while the exact ground surface temperature above the piles reduces the error to 0.03%.

Novel free surface boundary conditions for spilling breaking waves

2020 ◽  
Vol 159 ◽  
pp. 103717
Author(s):  
Nikta Iravani ◽  
Peyman Badiei ◽  
Maurizio Brocchini
Keyword(s):  
Free Surface ◽  
Boundary Conditions ◽  
Breaking Waves ◽  
Surface Boundary ◽  
Surface Boundary Conditions
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