scholarly journals Ocean atmospheric coupled model to estimate energy and path of cyclone near the coast

MAUSAM ◽  
2022 ◽  
Vol 64 (1) ◽  
pp. 189-192
Author(s):  
RAMKRISHNA DATTA
Keyword(s):  
Complex Potential ◽  
Fluid Motion ◽  
Coupled Model ◽  
Stream Velocity ◽  
Maximum Pressure ◽  
Image System ◽  
Object System ◽  
Bernoulli’S Equation ◽  
The Right ◽  
Atmospheric Phenomena

;g ns[kk x;k gS fd caxky dh [kkM+h esa vf/kdka’kr% pØokr] gjhdsu vkfn tSlh ok;qeaMyh; ifj?kVuk,¡ viuh xfr ds nk¡bZ vksj c<+rh gSaA ,lh ?kVukvksa dk v/;;u djus ds fy, geus ok;qeaMyh; xfr ;qfXer] egklkxj dh rjy xfrdh; ij fopkj fd;k gSA bl v/;;u esa geus pØokrh; ra= ds dsUnz dks fy;k gS ftlesa rjy xfrdh; lzksr rFkk FkksMh lh nwjh ij rjy xfrdh; flad gksrk gSA bl izdkj fcEc ra= ds rjy xfrdh; f}d ¼MCysV½ fufeZr gksrk gSA rnqijkar fcEc rjax vkSj mlds izfrfcEc rjax ds rjy xfrdh; f}d  ¼MCysV½ ij Bksl nhokj  ¼;gk¡ ij leqanz dk fdukjk½ ds laca/k esa fopkj fd;k x;kA blesa fcEc ra=] izfrfcEc ra= vkSj /kkjk xfr ls lacaf/kr fefJr fcEc ds rjy xfrdh; lehdj.k ij dk;Z fd;k x;k gSA fcEc ra=] izfrfcEc f}d ¼MCysV½ rFkk /kkjk xfr ds fefJr foHko ij bl 'kks/k i= esa fopkj fd;k x;k gSA xfr lfn’k] QyLo:i nkc dks rjy xfr ds cjukSyh ds lehdj.k dh lgk;rk ls iqu% izkIr fd;k x;kA rnqijkar leqnz ds fdukjs vFkkZr~ nhokj ij U;wure@vf/kdre nkc dh fo’ys"k.kkRed x.kuk dh xbZA vr% ;g ns[kk x;k fd pØokr vFkok gjhdsu dh ekStwnk iou vkSj ÅtkZ dqN izpfyr fLFkfr;ksa ds vk/kkj ij leqnz rV dh vksj vFkok mldh xfr ds nk¡bZ vksj tkrh gSA It is seen that in the Bay of Bengal or in the Gulf, most of the time the atmospheric phenomena, like, cyclone, hurricane etc. move towards right to its motion. To study such occurrences; we have considered fluid dynamics of ocean coupled with atmospheric motion. In the present study we have considered the eye of the cyclonic system that consist of fluid dynamical source and fluid dynamical sink at a small distance apart, and thus, constitute the fluid dynamical doublet of the object system. Then the fluid dynamical doublet of the object system and its image system has been considered with respect to a firm wall (here the sea shore). The fluid dynamical equation of complex potential with respect to the object system, the image system and the stream velocity have been undertaken. The complex potential of the object doublet, image doublet and the stream velocity have been considered. The velocity vector, consequently the pressure has been retrieve with the help of Bernoulli’s equation of fluid motion. Then the minimum /maximum pressure on the wall that is on the sea shore has been calculated analytically. Thus, it is found that on the basis of some prevailing conditions existing wind and energy the cyclone or hurricane move towards the sea coast or to the right of its motion.

scholarly journals A stable method for 4D CT-based CFD simulation in the right ventricle of a TGA patient

2020 ◽  
Vol 35 (5) ◽  
pp. 315-324
Author(s):  
Yuri Vassilevski ◽  
Alexander Danilov ◽  
Alexander Lozovskiy ◽  
Maxim Olshanskii ◽  
Victoria Salamatova ◽  
...  
Keyword(s):  
Right Ventricle ◽  
Cfd Simulation ◽  
Fluid Motion ◽  
4D Ct ◽  
Post Surgery ◽  
Surgery Patient ◽  
Time Dependent Domain ◽  
Flow Domain ◽  
The Right ◽  
Dependent Domain

AbstractThe paper discusses a stabilization of a finite element method for the equations of fluid motion in a time-dependent domain. After experimental convergence analysis, the method is applied to simulate a blood flow in the right ventricle of a post-surgery patient with the transposition of the great arteries disorder. The flow domain is reconstructed from a sequence of 4D CT images. The corresponding segmentation and triangulation algorithms are also addressed in brief.

scholarly journals The Electrostatic Energy of a Two-Dimensional System

1959 ◽  
Vol 42 ◽  
pp. 1-2
Author(s):  
LL. G. Chambers
Keyword(s):  
Complex Variable ◽  
Complex Potential ◽  
Unit Length ◽  
Electrostatic Energy ◽  
Dimensional System ◽  
Two Dimensional ◽  
Image System ◽  
Actual System ◽  
Image Domain ◽  
Two Dimensional System

The use of the complex variable z( = x + iy) and the complex potential W(= U + iV) for two-dimensional electrostatic systems is well known and the actual system in the (x, y) plane has an image system in the (U, V) plane. It does not seem to have been noticed previously that the electrostatic energy per unit length of the actual system is simply related to the area of the image domain in the (U, V) plane.

scholarly journals Bias in CMIP6 models as compared to observed regional dimming and brightening

2020 ◽  
Vol 20 (24) ◽  
pp. 16023-16040
Author(s):  
Kine Onsum Moseid ◽  
Michael Schulz ◽  
Trude Storelvmo ◽  
Ingeborg Rian Julsrud ◽  
Dirk Olivié ◽  
...  
Keyword(s):  
Sulfur Dioxide ◽  
Surface Energy ◽  
Coupled Model ◽  
Shortwave Radiation ◽  
Anthropogenic Aerosol ◽  
Surface Energy Fluxes ◽  
Aerosol Emission ◽  
Wrong Reason ◽  
The Right ◽  
Aerosol Emissions

Abstract. Anthropogenic aerosol emissions have increased considerably over the last century, but climate effects and quantification of the emissions are highly uncertain as one goes back in time. This uncertainty is partly due to a lack of observations in the pre-satellite era, making the observations we do have before 1990 additionally valuable. Aerosols suspended in the atmosphere scatter and absorb incoming solar radiation and thereby alter the Earth's surface energy balance. Previous studies show that Earth system models (ESMs) do not adequately represent surface energy fluxes over the historical era. We investigated global and regional aerosol effects over the time period 1961–2014 by looking at surface downwelling shortwave radiation (SDSR). We used observations from ground stations as well as multiple experiments from eight ESMs participating in the Coupled Model Intercomparison Project Version 6 (CMIP6). Our results show that this subset of models reproduces the observed transient SDSR well in Europe but poorly in China. We suggest that this may be attributed to missing emissions of sulfur dioxide in China, sulfur dioxide being a precursor to sulfate, which is a highly reflective aerosol and responsible for more reflective clouds. The emissions of sulfur dioxide used in the models do not show a temporal pattern that could explain observed SDSR evolution over China. The results from various aerosol emission perturbation experiments from DAMIP, RFMIP and AerChemMIP show that only simulations containing anthropogenic aerosol emissions show dimming, even if the dimming is underestimated. Simulated clear-sky and all-sky SDSR do not differ greatly, suggesting that cloud cover changes are not a dominant cause of the biased SDSR evolution in the simulations. Therefore we suggest that the discrepancy between modeled and observed SDSR evolution is partly caused by erroneous aerosol and aerosol precursor emission inventories. This is an important finding as it may help interpret whether ESMs reproduce the historical climate evolution for the right or wrong reason.

scholarly journals The problem of hydraulic calculation of pressure distribution pipelines

2021 ◽  
Vol 6 (7 (114)) ◽  
Author(s):  
Volodymyr Cherniuk ◽  
Roman Hnativ ◽  
Oleksandr Kravchuk ◽  
Vadym Orel ◽  
Iryna Bihun ◽  
...  
Keyword(s):  
Pressure Distribution ◽  
Flow Rate ◽  
Calculation Method ◽  
Fluid Motion ◽  
Hydraulic Calculation ◽  
Calculation Methods ◽  
Production Technologies ◽  
The Right ◽  
Longitudinal Slot ◽  
Resistance Coefficients

Most production technologies require a uniform flow path of liquid from pressure distribution pipelines. To achieve this goal, it is proposed to introduce polymer additives into the liquid flow or to use converging distribution pipelines with a continuous longitudinal slot in the wall. To reduce the uneven operation of the distribution pipeline during discrete liquid dispensing, it is proposed to use cylindrical output rotary nozzles with a lateral orthogonal entry of the jet into the nozzle. The problem is the lack of methods for accurate hydraulic calculation of the operation of distribution pipelines. Adequate calculation methods are based on differential equations. Finding the exact solution of the differential equation of fluid motion with variable path flow rate for perforated distribution pipelines is urgent, because it still does not exist. The available calculation methods take into account only the right angles of separation of the jets from the flow in the distribution pipeline. These methods are based on the assumption that the coefficient of hydraulic friction and the coefficient of resistance of the outlets are constant along the flow. A calculation method is proposed that takes into account the change in the values of these resistance coefficients along the distribution pipeline. The kinematic and physical characteristics of the flow outside the distribution pipeline are also taken into account. The accuracy of calculating the value of the flow rate of water distributed from the distribution pipeline has been experimentally verified. The error in calculating the water consumption by the method assuming that the values of the resistance coefficients are unchanged along the distribution pipeline reaches 18.75 %. According to the proposed calculation method, this error does not exceed 6.25 %. However, both methods are suitable for the design of pressure distribution pipelines, provided that the jet separation angles are straight. Taking into account the change from 90° to 360° of the angle of separation of the jets from the flow in the distribution pipeline will expand the scope and accuracy of calculation methods.

scholarly journals Research on Oscillating Characteristics of the Shear Layer on the Ship Bottom with a Moonpool under the Action of the Current and Wave

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
X. H. Huang ◽  
X. L. Yao ◽  
Z. Y. Shi ◽  
W. Xiao
Keyword(s):  
Shear Layer ◽  
High Speed ◽  
Fluid Motion ◽  
Acoustic Detection ◽  
High Speed Flow ◽  
Bubble Generation ◽  
Speed Flow ◽  
The Right ◽  
The Impact ◽  
Oscillating Characteristics

For some research vessels, a sonar is installed in the moonpool, and some acoustic detection equipment are installed on the ship bottom behind the moonpool, which helps to avoid the impact of the high-speed flow. The moonpool causes the ship bottom discontinued, forming a particular shear layer oscillation. The shear layer oscillation affects the bubble generation and motion in and behind the moonpool. The sonar and acoustic equipment will malfunction when surrounded by many bubbles. However, there is almost no research on the shear layer oscillation near the moonpool. So, in this paper, by measuring the pressure near the moonpool and monitoring the fluid motion in the moonpool and bubbles’ distribution along the ship bottom, the shear layer oscillation near the moonpool is studied experimentally under the action of the incident current and wave. Furthermore, the effects of the sonar and the moonpool shape are investigated. It can be seen that the shear layer oscillation excites the fluid motion in the moonpool. The sonar forms a complicated boundary in the moonpool, resulting in the increase in the frequency of the shear layer oscillation. The shear layer propagates along the ship bottom in the form of the ship bottom wave. Clarifying the oscillating characteristics of the shear layer along the ship bottom with a moonpool is conducive to the design of moonpools in the research ships, and the detection instruments are arranged in the right place along the ship bottom, so as to make sure the detection instruments work properly and detect the marine environment more accurately.

scholarly journals Effects of local activation times on the tension development of human cardiomyocytes in a computational model

2018 ◽  
Vol 4 (1) ◽  
pp. 247-250
Author(s):  
Armin Müller ◽  
Ekaterina Kovacheva ◽  
Steffen Schuler ◽  
Olaf Dössel ◽  
Lukas Baron
Keyword(s):  
Human Heart ◽  
Maximum Pressure ◽  
Simulation Framework ◽  
Activation Time ◽  
Tension Development ◽  
Human Cardiomyocytes ◽  
Local Activation ◽  
Activation Times ◽  
The Right ◽  
Simulation Time

AbstractThe human heart is an organ of high complexity and hence, very challenging to simulate. To calculate the force developed by the human heart and therefore the tension of the muscle fibers, accurate models are necessary. The force generated by the cardiac muscle has physiologically imposed limits and depends on various characteristics such as the length, strain and the contraction velocity of the cardiomyocytes. Another characteristic is the activation time of each cardiomyocyte, which is a wave and not a static value for all cardiomyocytes. To simulate a physiologically correct excitation, the functionality of the cardiac simulation framework CardioMechanics was extended to incorporate inhomogeneous activation times. The functionality was then used to evaluate the effects of local activation times with two different tension models. The active stress generated by the cardiomyocytes was calculated by (i) an explicit function and (ii) an ode-based model. The results of the simulations showed that the maximum pressure in the left ventricle dropped by 2.3% for the DoubleHill model and by 5.3% for the Lumens model. In the right ventricle the simulations showed similar results. The maximum pressure in both the left and the right atrium increased using both models. Given that the simulation of the inhomogeneously activated cardiomyocytes increases the simulation time when used with the more precise Lumens model, the small drop in maximum pressure seems to be negligible in favor of a simpler simulation model

scholarly journals The method of images in some problems of surface waves

1927 ◽  
Vol 115 (771) ◽  
pp. 268-280 ◽  
Keyword(s):  
Free Surface ◽  
Circular Cylinder ◽  
Surface Waves ◽  
Unit Length ◽  
Wave Length ◽  
Fluid Motion ◽  
Degree Of Approximation ◽  
Image Point ◽  
Horizontal Line ◽  
Image System

1. When a circular cylinder is submerged in a uniform stream, the surface elevation may be calculated, to a first approximation, by a method due originally to Lamb for this case, and later extended to bodies of more general form: the method consists in replacing the cylinder by the equivalent doublet at its centre and then finding the fluid motion due to this doublet. In discussing the problem some years ago, I remarked that if the solution so obtained were interpreted in terms of an image system of sources, we should then be able to proceed to further approximations by the method of successive images, taking images alternately in the surface of the submerged body and in the free surface of the stream. This is effected in the following paper for two-dimensional fluid motion, and the method is applied to the circular cylinder. It provides, theoretically at least, a process for obtaining any required degree of approximation but, of course, the expressions soon become very complicated. It is, however, of interest to examine some cases numerically so as to obtain some idea of the degree of approximation of the first stage. An expression is first obtained for the velocity potential of the fluid motion due to a doublet at a given depth below the surface of a stream, the doublet being of given magnitude with its axis in any direction. A transformation of this expression then gives a simple interpretation in terms of an image system. This system consists of a certain isolated doublet at the image point above the free surface, together with a line distribution of doublets on a horizontal line to the rear of this point; the moment per unit length of the line distribution is constant, but the direction of the axis rotates as we pass along the line, the period of a revolution being equal to the wave-length of surface waves for the velocity of the stream. The contribution of each part of the image system to the surface disturbance is indicated.

Bias in CMIP6 models compared to observed regional dimming and brightening trends (1961-2014)

2020 ◽  
Author(s):  
Kine Onsum Moseid ◽  
Michael Schulz ◽  
Trude Storelvmo ◽  
Ingeborg Rian Julsrud ◽  
Dirk Olivié ◽  
...  
Keyword(s):  
Coupled Model ◽  
Shortwave Radiation ◽  
Anthropogenic Aerosol ◽  
Surface Energy Fluxes ◽  
Aerosol Emission ◽  
Wrong Reason ◽  
The Right ◽  
Aerosol Effects ◽  
Aerosol Emissions ◽  
Trend Reversal

&lt;p&gt;Anthropogenic aerosol emissions have increased considerably over the last century, but climate effects and quantification of the emissions are highly uncertain as one goes back in time. This uncertainty is partly due to a lack of observations in the pre-satellite era, and previous studies show that Earth system models (ESMs) do not adequately represent surface energy fluxes over the historical era. We investigated global and regional aerosol effects over the time period 1961-2014 by looking at surface downwelling shortwave radiation (SDSR).&lt;br&gt;We used observations from ground stations as well as multiple experiments from five ESMs participating in the Coupled Model Intercomparison Project Version 6 (&lt;em&gt;CMIP6&lt;/em&gt;). Our results show that this subset of models reproduces the observed transient SDSR well in Europe, but poorly in China.&amp;#160;&lt;br&gt;The models do not reproduce the observed trend reversal in SDSR in China in the late 1980s, which is attributed to a change in the emission of SO&lt;sub&gt;2&lt;/sub&gt; in this region. The emissions of SO&lt;sub&gt;2&lt;/sub&gt; show no sign of a trend reversal that could explain the observed SDSR evolution over China, and neither do other aerosols relevant to SDSR. The results from various aerosol emission perturbation experiments from &lt;em&gt;DAMIP&lt;/em&gt;, &lt;em&gt;RFMIP&lt;/em&gt; and &lt;em&gt;AerChemMIP&lt;/em&gt; suggest that its likely, that aerosol effects are responsible for the dimming signal, although not its full amplitude. Simulated cloud cover changes in the different models are not correlated with observed changes over China.&amp;#160; Therefore we suggest that the discrepancy between modeled and observed SDSR evolution is partly caused by erroneous aerosol and aerosol precursor emission inventories. This is an important finding as it may help interpreting whether ESMs reproduce the historical climate evolution for the right or wrong reason.&lt;/p&gt;

Instability Analysis of Coupling Seepage and Stress Field in Unsaturated Soil

2013 ◽  
Vol 446-447 ◽  
pp. 1448-1455
Author(s):  
Ji Wei Li ◽  
Hua Bing Wang ◽  
Ling Zhang
Keyword(s):  
Stress Field ◽  
Unsaturated Soil ◽  
Fluid Motion ◽  
Coupled Model ◽  
Linear Instability ◽  
Instability Analysis ◽  
Wet Process ◽  
Field Coupling ◽  
Stability Change ◽  
Linear Instability Analysis

The instability of seepage and stress field coupling in unsaturated soil caused by wet process, resulted stability change in unsaturated soil.Thus,it is important to analysis the conditions of the coupling stability not in theory but in engineering. A coupled seepage and stress field model was derived from the transport laws in continuum mechanics and Darcy's law, integrated with fluid motion in porous media. Then, a linear instability analysis was performed to investigate the general conditions of which kind would trigger the non-stability of the coupling field. Finally, some variables, which have a significant effect on the onset of the instability of the unsaturated system subjected to the instability of the coupled model, were proposed in some simplified conditions.

A Comparison of the Influence of Additive and Multiplicative Stochastic Forcing on a Coupled Model of ENSO

2005 ◽  
Vol 18 (23) ◽  
pp. 5066-5085 ◽  
Author(s):  
Cristina L. Perez ◽  
Andrew M. Moore ◽  
Javier Zavala-Garay ◽  
Richard Kleeman
Keyword(s):  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Low Frequency ◽  
Coupled Model ◽  
Deterministic System ◽  
Low Frequency Oscillation ◽  
Stochastic Forcing ◽  
Integration Period ◽  
Atmospheric Phenomena

Abstract A currently popular idea is that El Niño–Southern Oscillation (ENSO) can be viewed as a linear deterministic system forced by noise representing processes with periods shorter than ENSO. Also, there is observational evidence to suggest that the Madden–Julian oscillation (MJO) acts to trigger and/or amplify the warm phase of ENSO in this way. The feedback of the slower process, ENSO, to higher-frequency atmospheric phenomena, of which a large part of the variability in the intraseasonal band is due to the MJO, has received little attention. This paper considers the hypothesis that the probability of an El Niño event is modified by high MJO activity and that, in turn, the MJO is regulated by ENSO activity. If this is indeed the case, then viewing ENSO as a low-frequency oscillation forced by additive stochastic noise would not present a complete picture. This paper tests the above hypothesis using a stochastically forced intermediate coupled model by allowing ENSO to directly influence the stochastic forcing. The model response to a variety of stochastic forcing types is found to be sensitive to the type of forcing applied. When the model is operated beyond its intrinsic Hopf bifurcation, its probability distribution function (PDF) is fundamentally altered when the stochastic forcing is changed from additive to multiplicative. The model integration period also influences the shape of the PDF, which is also compared to the PDF derived from observations. It is found that multiplicative stochastic forcing reproduces some measures of the observations better than the additive stochastic forcing.

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