Search results for " Hydrodynamic"
showing 10 items of 121 documents
The mathematical modeling of the single and ensemble dynamics of magnetic filaments
2016
Biomimētisku sistēmu izmantošana mikrodzinēju un šķidrumu maisītāju izveidei ir aktuāls izpētes objekts mīksto materiālu nozarē. Šiem mērķiem iespējams izmantot magnētiskas stīgas, ko ir viegli kontrolēt mainot ārēja magnētiskā lauka parametrus. Šajā darbā ir izveidots magnētisku stīgu matemātisks modelis, kas ietver gan vērp es, gan hidrodinamisko mijiedarbību ietekmi dažādos tuvinājumos un izveidota praktiska implementācija divu programmatūras bibliotēku formā. Ar izveidotā modeļa palīdzību iegūti rezultāti, kas raksturo individuālu stīgu un stīgu ansambļu dinamika plašā kustību kontrolējošo parametru diapazonā un iegūti jauni rezultāti, kas raksturo feromagnētisku un superparamagnētisku …
A fast multi-dimensional magnetohydrodynamic formulation of the transition region adaptive conduction (TRAC) method
2021
We have demonstrated that the Transition Region Adaptive Conduction (TRAC) method permits fast and accurate numerical solutions of the field-aligned hydrodynamic equations, successfully removing the influence of numerical resolution on the coronal density response to impulsive heating. This is achieved by adjusting the parallel thermal conductivity, radiative loss, and heating rates to broaden the transition region (TR), below a global cutoff temperature, so that the steep gradients are spatially resolved even when using coarse numerical grids. Implementing the original 1D formulation of TRAC in multi-dimensional magnetohydrodynamic (MHD) models would require tracing a large number of magne…
A mesoscopic mechanical model of the surface tension and some simulation results
2019
Abstract Drops of mercury do not spread on a surface. A metal paper clip can float on water. These phenomena are macroscopic manifestations of molecular interactions and can be explained in terms of surface tension. In this study, we discuss a simple mesoscopic mechanical model of the surface tension and the results of numerical fluid dynamics simulations implemented on the basis of it. We study the droplet formation without and with gravity when it can drop from a narrow hole like a trickling tap and finally the behaviour of free surface liquid in a vessel. Teachers and students can be able to study the surface tension by using the computer simulation as a “tool” for analysing and discussi…
Computer simulations to approach surface tension by means of a simple mesoscopic mechanical model
2019
A small insect can stand or walk on water surface, drops of mercury do not spread on a solid surface, and a meniscus is formed at the free surface of a liquid contained in a thin vessel. These phenomena can be seen as macroscopic manifestations of molecular interactions and can be explained macroscopically in terms of surface tension. In this study, we deal with an approach to surface tension from a mechanical point of view, presenting a simple mesoscopic mechanical model of surface tension and the results of its implementation in numerical fluid dynamics simulations. Particularly, phenomena like droplet formation without gravity and with gravity when it can drop from a narrow hole like a t…
A practical methodology to perform global sensitivity analysis for 2D hydrodynamic computationally intensive simulations
2021
Sensitivity analysis is a commonly used technique in hydrological modeling for different purposes, including identifying the influential parameters and ranking them. This paper proposes a simplified sensitivity analysis approach by applying the Taguchi design and the ANOVA technique to 2D hydrodynamic flood simulations, which are computationally intensive. This approach offers an effective and practical way to rank the influencing parameters, quantify the contribution of each parameter to the variability of the outputs, and investigate the possible interaction between the input parameters. A number of 2D flood simulations have been carried out using the proposed combinations by Taguchi (L27…
Persistent episomal transgene expression in liver following delivery of a scaffold/matrix attachment region containing non-viral vector
2008
An ideal gene therapy vector should enable persistent transgene expression without limitations of safety and reproducibility. Here we report the development of a non-viral episomal plasmid DNA (pDNA) vector that appears to fulfil these criteria. This pDNA vector combines a scaffold/matrix attachment region (S/MAR) with a human liver-specific promoter (alpha1-antitrypsin (AAT)) in such a way that long-term expression is enabled in murine liver following hydrodynamic injection. Long-term expression is demonstrated by monitoring the longitudinal luciferase expression profile for up to 6 months by means of in situ bioluminescent imaging. All relevant control pDNA constructs expressing luciferas…
Development of S/MAR minicircles for enhanced and persistent transgene expression in the mouse liver.
2010
We have previously described the development of a scaffold/matrix attachment region (S/MAR) episomal vector system for in vivo application and demonstrated its utility to sustain transgene expression in the mouse liver for at least 6 months following a single administration. Subsequently, we observed that transgene expression is sustained for the lifetime of the animal. The level of expression, however, does drop appreciably over time. We hypothesised that by eliminating the bacterial components in our vectors, we could improve their performance since bacterial sequences have been shown to be responsible for the immunotoxicity of the vector and the silencing of its expression when applied i…
A computational framework for coating fatigue analysis of wind turbine blades due to rain erosion
2021
Author's accepted manuscript The rain-induced fatigue damage in the wind turbine blade coating has attracted increasing attention owing to significant repair and maintenance costs. The present paper develops an improved computational framework for analyzing the wind turbine blade coating fatigue induced by rain erosion. The paper first presents an extended stochastic rain field simulation model that considers different raindrop shapes (spherical, flat, and spindle), raindrop sizes, impact angles, and impact speeds. The influence of these raindrop characteristics on the impact stress of the blade coating is investigated by a smoothed particle hydrodynamics approach. To address the expensive …
Experimental observation of the rule of flexible vegetation on erosion processes
2012
Vegetation altering hydrodynamic conditions of an open channel flow controls the exchanges of sediment, nutrients and contaminants. Thus, the knowledge of the hydraulic characteristics of flow over vegetation is very important to support the management of fluvial processes. But, the analysis of the hydrodynamic conditions is complex because vegetation is flexible in varying degrees and it oscillates in the flow changing position. Furthermore, because of temporal changing of roughness due to natural vegetative growth, the response of vegetation to the flow can change in time. Many theoretical and experimental investigations have been performed in order to analyze both the mean flow and turbu…
Comparing two methods to perform a beerkan infiltration run in a loam soil at different dates
2023
<p>Performing beerkan infiltration runs with different heights of water pouring could help to obtain saturated soil sorptivity, <em>S</em>, and hydraulic conductivity, <em>K<sub>s</sub></em>, data usable to explain and simulate hydrological processes. However, most of the available information on the L (low height of water pouring, nearly 3 cm) - H (high height, 1-2 m) methodology refers to runs making use of a relatively limited number of water volumes and there is some sign that a few water volumes could yield an incomplete description of soil alteration phenomena induced by wetting. For a lo…