Study about the mechanical energy balance and the energy loss of 3-D turbulent flows in open-channels has its own complexities. The governing equation of the mechanical energy in turbulent flows has been previously known and includes turbulence parameters that their calculations or measurements are not easy. In this study, a form of the total mechanical energy equation that leads to a number of significant physical insights is analytically investigated, from which analytical relationships for the energy loss estimation in 3-D turbulent flows are defined. The effect of different turbulence parameters is reflected on the new relationships and analyzed by equalizations replacing unknown correlations with closure approximations using the numerical turbulence simulation. In order to investigate the application of the analytical relationships, numerical simulations are performed by using OpenFOAM software to solve the Navier-Stokes equations with the RSM turbulence model in open-channels with different geometries. Then, the contribution of the turbulence parameters to the total mechanical energy balance is evaluated in uniform and nonuniform turbulent flows and their difference is analyzed, that leads to identify the parameters affecting the friction and local losses. The results demonstrate that the magnitudes of the turbulent diffusion, the work done by the viscous stresses pertaining to the mean motion and the viscous diffusion of the turbulence energy are substantially smaller than the other terms of the total energy equation for turbulent flows in open-channels with different geometries, while the effect of the variations of the turbulence kinetic energy and the work done by the turbulence stresses, that has not been considered in the previous mechanical energy equations, is more important in complex flows. From a practical viewpoint, in order to study the details of the total mechanical energy balance and the energy loss in 3-D turbulent flows with the presence of the secondary currents, the proposed method can be useful.
Einstein-Barbarossa velocity or resistance equation (1952) is widely used to find resistance to flow in alluvial channel. In order to validate the equation in all ranges (smooth to rough); they introduced a correction factor based on the Nikuradse measurement. This correction factor is determined from the graphical method, which can be erroneous. Present work reanalyzes the Nikuradse measurements and gives an analytical formulation for the correction factor. and Einsteinova-Barbarossova rovnica (1952) sa často používa na určenie odporu voči prúdeniu v kanáloch. Autori do nej zaviedli korekčný faktor, založený na meraniach Nikuradzeho, aby overili platnosť rovnice v celom rozsahu drsností (od hladkých stien po drsné). Tento korekčný faktor sa určuje grafickou metódou, ktorá môže viesť k chybným výsledkom. V tejto práci sa znova analyzujú výsledky Nikuradzeho meraní a je navrhnutá analytická formulácia na výpočet korekčného faktora.
This paper presents closed form solution for unsteady flow equation corresponding to the transient hydraulic head, flow rate and volumetric exchange of a confined aquifer which is in contact with a constant piezometric head at one end and a stream whose water level is rising at a constant rate at the other end. The aquifer is also subjected to receive constant inflow due to rain infiltration. The unsteady groundwater flow equation is solved using Laplace transform to get analytical expressions for the transient hydraulic head and flow rate at the left and right interfaces and the net volumetric exchange of water at the aquifer-stream interface. The analytical results presented here show the effect of recharge due to rain infiltration on the net volumetric exchange and reveal the conditions for which net inflow in the aquifer could be positive, negative or zero. The results obtained have the capability to determine transient hydraulic head for two extreme scenarios: (i) very slow rise and (ii) very fast rise in the stream water. Analytical result show that the net volumetric exchange could be positive, zero or negative depending on the surface infiltration and stream water rise rate. and Príspevok obsahuje analytické riešenie rovnice neustáleného prúdenia vzhľadom na neustálenú hydraulickú výšku, rýchlosť prúdenia a objemové toky vo zvodnenom kolektore s napätou hladinou, ktorý je v kontakte s konštantnou piezometrickou výškou na jednej strane a s tokom s konštantne sa zvyšujúcou hladinou vody na strane druhej. Zvodnený kolektor je tiež napájaný konštantnou rýchlosťou infiltrovanou vodou zo zrážok. Rovnica neustáleného prúdenia podzemnej vody je riešená s použitím Laplaceovej transformácie, aby sme získali neustálenú tlakovú výšku na ľavej aj pravej strane a objemový prítok vody na rozhraní zvodnený kolektor - tok. Výsledky analytického riešenia, ktoré predkladáme, ukazujú vplyv infiltrácie zrážok na doplňovanie podzemnej vody a odhaľujú podmienky, za ktorých prítok do zvodneného kolektora môže byť kladný, negatívny, alebo nulový. Získané výsledky umožňujú určiť neustálené hydraulické výšky pre dva extrémne scenáre: (i) veľmi pomalé a (ii) veľmi rýchle zvýšenie hladiny vody v toku. Analytické riešenie ukazuje, že objem vody, ktorou je zvodnený kolektor doplňovaný, môže byť kladný, záporný, alebo nulový, v závislosti na intenzite infiltrácie a rýchlosti zvyšovania sa hladiny vody v toku.
An analytical solution for the two-dimensional tension leg platform (TLP) interacting with ocean wave is presented. The legs of TLP are considered as elastic springs. The flow is assumed to be irrotational and single-valued velocity potentials are defined. The effects of radiation and scattering are considered in the boundary value problem. Because of linear behavior of legs during wave excitation, ignoring coupling effects with other degrees of freedom, the analytical solution of heave response has good agreement with the real behavior of the structure. and Práce uvádí analytické řešení působení vln na dvoudimenzionální pevně ukotvenou plošinu (TLP). Úchyty plošiny jsou uvažovány jako elastické pružiny. Předpokládá se nevírový tok a je definováno jednoznačné rychlostní pole. Okrajové podmínky zahrnují vlivy radiace a rozptylu. Předpoklad lineárního chování úchytů při excitaci mořskými vlnami i zanedbání některých dalších efektů v analytickém řešení odezvy TLP na vznášení ukázaly, že existuje soulad mezi naším řešením a skutečným chováním konstrukce.
After bark beetle calamity in National park Šumava were established three experimental catchments with different forest cover (dead forest, clearing and healthy forest). In these catchments were, in period without snow cover, measured components of rainfall-runoff events. The aim of the research was to estimate a correlation of chosen characteristics of rainfall-runoff events from catchments Modrava 1 (dead forest) and Modrava 2 (clearing). Comparing limit values of correlations, there were found no significant differences between observed catchments. and Po kůrovcové kalamitě v Národním parku Šumava vznikla na plochách s rozdílným pokryvem (stojící odumřelý smrkový les, paseka a zdravý les) tři experimentální povodí. Na těchto povodích byly v období bez sněhové pokrývky měřeny komponenty srážkoodtokového procesu. Předmětem výzkumu bylo stanovení vzájemných závislostí vybraných komponent srážkoodtokových událostí na povodích Modrava 1 (odumřelý les) a Modrava 2 (paseka). Při porovnání limitních hodnot vybraných závislostí nebyly patrné mezi zkoumanými experimentálními povodími výrazné rozdíly.
The paper is aimed at the subject and spatial analyses of flood situations that occurred in Slovakia in the period 1996-2006. The subject analysis include analysis of flood situations frequency in communities of Slovakia, classification of flood situations into individual types, analysis of flood situations occurrence regarding the stream size, and a brief characteristics of the most important floods that occurred in Slovakia in the period 1996-2006. Spatial analysis is focused on: a) identification of pattern in spatial distribution of flood situations, b) explanation of spatial distribution of flood situations by means of regional variability of flood hazard in small basins of Slovakia. and Príspevok je zameraný na vecnú a priestorovú analýzu povodňových situácii, ktoré sa vyskytli v obciach Slovenska v období r. 1996-2006. Vecná analýza zahrňuje analýzu frekvencie výskytu povodňových situácií v obciach Slovenska, klasifikáciu povodňových situácií do typov, analýzu výskytu povodňových situácií vzhľadom na veľkosť vodného toku, ako aj stručnú charakteristiku najvýznamnejších povodňových situácií v období 1996-2006. Priestorová analýza je zameraná na: a) identifikovanie konfigurácie v priestorovom rozložení výskytu povodňových situácií, b) objasnenie priestorového rozloženia povodňových situácií prostredníctvom regionálnej variability povodňovej hrozby v malých povodiach Slovenska.
Lockean theories of personal identity maintain that we per-sist by virtue of psychological continuity, and most Lockeans say that we are material things coinciding with animals. Some animalists ar-gue that if persons and animals coincide, they must have the same intrinsic properties, including thinking, and, as a result, there are ‘too many thinkers’ associated with each human being. Further, Lockeans have trouble explaining how animals and persons can be numerically different and have different persistence conditions. For these reasons, the idea of a person being numerically distinct but coincident with an animal is rejected and animalists conclude that we simply are animals. However, animalists face a similar problem when confronted with the vagueness of composition. Animals are entities with vague boundaries. According to the linguistic account of vagueness, the vagueness of a term consists in there being a number of candidates for the denotatum of the vague term. It seems to imply that where we see an animal, there are, in fact, a lot of distinct but overlapping entities with basically the same intrinsic properties, including think-ing. As a result, the animalist must also posit ‘too many thinkers’ where we thought there was only one. This seems to imply that the animalist cannot accept the linguistic account of vagueness. In this paper the author argues that the animalist can accept the linguistic account of vagueness and retain her argument against Lockeanism.