Search

Start Over Subject hydrodynamics

1. Challenges to the theories of B stars circumstellar environment

Creator:
Krtička, J., Korčáková, D., and Kubát, J.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
stars: winds, stars: outflows, stars: mass-loss, stars: early-type, hydrodynamics, and instabilities
Language:
Czech
Description:
We review recent developments in the field of B stars circumstellar environment modelling and discuss future improvements which are necessary to obtain more realistic models of the circumstellar environment of B stars.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

2. Floods effects on rivers morphological changes application to the Medjerda River in Tunisia

Creator:
Gharbi, Mohamed, Soualmia, Amel, Dartus, Denis, and Masbernat, Lucien
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
floods, hydrodynamics, sediment transport, modelling, and river morphology
Language:
Slovak
Description:
In Tunisia especially in the Medjerda watershed the recurring of floods becoming more remarkable. In order to limit this risk, several studies were performed to examine the Medjerda hydrodynamic. The analysis of results showed that the recurrences of floods at the Medjerda watershed is strongly related to the sediment transport phenomena. Initially, a one dimensional modelling was conducted in order to determine the sediment transport rate, and to visualize the river morphological changes during major floods. In continuity of this work, we will consider a two-dimensional model for predicting the amounts of materials transported by the Medjerda River. The goal is to visualize the Medjerda behaviour during extreme events and morphological changes occurred following the passage of the spectacular flood of January 2003. As a conclusion for this study, a comparative analysis was performed between 1D and 2D models results. The objective of these comparisons is to visualize the benefits and limitations of tested models. The analysis of the results demonstrate that 2D model is able to calculate the flow variation, sediment transport rates, and river morphological changes during extreme events for complicated natural domains with high accuracy comparing with 1D Model.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

3. Modelling free surface flow with curvilinear streamlines by a non-hydrostatic model

Creator:
Zerihun, Yebegaeshet T.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
curvilinear flow, finite difference method, hydraulic structures, hydrodynamics, non-hydrostatic pressure, and nonuniform flow
Language:
Slovak
Description:
This study addresses a particular phenomenon in open channel flows for which the basic assumption of hydrostatic pressure distribution is essentially invalid, and expands previous suggestions to flows where streamline curvature is significant. The proposed model incorporates the effects of the vertical curvature of the streamline and steep slope, in making the pressure distribution non-hydrostatic, and overcomes the accuracy problem of the Saint-Venant equations when simulating curvilinear free surface flow problems. Furthermore, the model is demonstrated to be a higher-order one-dimensional model that includes terms accounting for wave-like variations of the free surface on a constant slope channel. Test results of predicted flow surface and pressure profiles for flow in a channel transition from mild to steep slopes, transcritical flow over a short-crested weir and flow with dual free surfaces are compared with experimental data and previous numerical results. A good agreement is attained between the experimental and computed results. The overall simulation results reveal the satisfactory performance of the proposed model in simulating rapidly varied gravity-driven flows with predominant non-hydrostatic pressure distribution effects. This study suggests that a higher-order pressure equation should be used for modelling the pressure distribution of a curvilinear flow in a steeply sloping channel.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

4. Some interesting hydrodynamical problems relating to binary stars

Creator:
Shore, Steven N.
Type:
model:article and TEXT
Subject:
accretion disks, hydrodynamics, and Algol binaries
Language:
Czech
Description:
This short review highlights some open questions regarding the dynamics of accretion disks in Algol and related systems. Standard disk theory hes been quite sucessful in cataclysmics, prostellar thick disks, and active galactic nuclei, but our understanding of relatively normal accretion flows remains less satisfactory. Some problems that remain unanswered include the treatment of the Roche surface as a limiting radius, the structure of Algol disks and viscous accretion, and boundary layer.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public