| ATTRIBUTE | VALUE |
|---|---|
| type | C |
| database id | 3834 |
| title | |
| authors | |
| affiliations | |
| year | 1997 |
| series | Archives of Hydro-Engineering and Environmental Mechanics |
| issue | Vol. 44, No. 1-4 |
| publisher | Wydawnictwo IBW PAN |
| place | Gdańsk |
| attributes | [published] [reviewed] [scientific] [international reach] |
| language | en |
| ATTRIBUTE | VALUE |
|---|---|
| type | A |
| database id | 5029 |
| title | The preliminary analysis of possibilities of the application of conventional flow-meters in measurements of unsteady flows |
| authors | Janusz Pospolita |
| pages | 23 — 44 |
| full text link | http://www.ibwpan.gda.pl/storage/app/media/ahem/ahem44no14str023.pdf |
| affiliations | |
| abstracts | The paper presents the state-of-art concerning possibilities of measurements of unsteady flows with flowmeters applied in practice as well as the results of test made by the author in this field. One-dimensional mathematical models joining the fluid flux, changeable at time, with the flowmeters indications were derived. These models were applied for estimation of influence of unsteady flow states on the additional error of measurement of instantaneous or mean value of the fluid flux. The analysis included periodically variable flows and flow changes in form of velocity jump. On the basis of the proposed mathematical models functions of flowmeter transition were derived, their time constants were determined and amplitude-frequency characteristics were presented. The spatial and time distributions of fluid velocities and pressures near the flowmeters were used for analysis of simplifying assumptions, assumed for formulation of one-dimensional models and estimation of the variability change of coefficients of the models versus time. These quantities were obtained by solving Reynolds equations and k-e model of turbulence in the flow system having geometry corresponding to a given flowmeter. The finite difference method was applied. Mathematical models for particular types of flowmeters, their time constants and values of dynamic errors were compared. The maximum ranges of model coefficients variability for flow changes (velocity jump) for different Strouhal numbers Sh, characterizing unsteady flows, were compared too. Conclusions of metrological character, determining possibilities of application of the flowmeters tested for measurements of unsteady flowmeters, were formulated. |
| attributes | [reviewed] [scientific] |
| language | en |
| ATTRIBUTE | VALUE |
|---|---|
| type | A |
| database id | 3888 |
| title | Numerical simulation of the biochemical oxygen demand and dissolved oxygen in the channels network |
| authors | Romuald Szymkiewicz, Kazimierz Burzyński |
| pages | 3 — 22 |
| full text link | http://www.ibwpan.gda.pl/storage/app/media/ahem/ahem44no14str003.pdf |
| affiliations | |
| abstracts | The paper deals with modelling of two indicators characterizing oxygen conditions of a river, which are: biochemical oxygen demand (BOD) and dissolved oxygen (DO). To describe the evolution of these two indicators, advection-diffusion transport equations are used. To solve these equations the decomposition technique is proposed. This approach enables the splitting up of the advection-diffusion equation into parts and independent solving of both parts in each time step. The advection equation is solved by the characteristics method with the spline function used in interpolation. To solve the diffusion equation the finite-elements method with the Crank-Nicolson scheme to integrate in time is applied. The proposed method ensures very small numerical errors. The method was tested using the known analytical solution and the results of measurements for the Reda river. |
| attributes | [reviewed] [scientific] |
| language | en |
| ATTRIBUTE | VALUE |
|---|---|
| type | A |
| database id | 5032 |
| title | Flow friction forces effect on barotropic wave attenuation in river mouth |
| authors | Zygmunt Meyer, Ryszard Ewertowski |
| pages | 45 — 67 |
| full text link | http://www.ibwpan.gda.pl/storage/app/media/ahem/ahem44no14str045.pdf |
| affiliations | |
| abstracts | The paper presents an analysis of barotropic wave attenuation in the river outlet distance due to friction forces at the bottom opposing the flow. The analysis concerns various types of barotropic waves and different velocities of wave propagation. As the results in comes that barotropic waves produce significant changes in free water surface elevation. The changes depend on waves properties but it seems to be that the most significant factor is the so called incidence angle which describes way of increment of barotropic pressure. |
| attributes | [reviewed] [scientific] |
| language | en |
| ATTRIBUTE | VALUE |
|---|---|
| type | A |
| database id | 5043 |
| title | Dynamics of variable declining rate filters during backwash |
| authors | Wojciech Dąbrowski, Ian R. Mackie |
| pages | 69 — 83 |
| full text link | http://www.ibwpan.gda.pl/storage/app/media/ahem/ahem44no14str069.pdf |
| affiliations | |
| abstracts | Variable declining rate (VDR) filters are usually controlled by the interaction of laminar head losses in the filter beds and turbulent head losses in the drainage systems and orifices installed at the outflow of each filter. The non-linear turbulent head losses are much higher for clean filters, but as the filter media becomes clogged the flow rate is reduced and the turbulent head losses decline. The disconnection of one filter during backwash causes a sudden increase in the water table level above the remaining filters, and so produces a rapid increase in the flow rates through them. This change in flow rate can have a significant impact on effluent quality. A simple and efficient method of calculating acceleration at the beginning of a backwash has been developed and verified by numerical solutions of the equations governing the hydraulics of VDR filters. The results show that the flow rate increases are approximately proportional to the flow rates during normal plant operation. A practical method of calculating the highest possible water table fluctuation during backwash has been developed. |
| attributes | [reviewed] [scientific] |
| language | en |
| ATTRIBUTE | VALUE |
|---|---|
| type | A |
| database id | 5069 |
| title | Channels with controlled average flow velocity |
| authors | Hanna Majcherek |
| pages | 85 — 110 |
| full text link | http://www.ibwpan.gda.pl/storage/app/media/ahem/ahem44no14str085.pdf |
| affiliations | |
| abstracts | A method of channels with controlled flow velocity designing is presented and experimentally verified. Proportional weirs at the outlets of the channel are used as velocity controlling devices. Studies are carried out for one and two-part weirs with discharge characteristic described by a power function. The conditions for practical shapes of the channel and weir are determined. This paper also presents particular solutions for the different discharge characteristic of the weir and velocity characteristic in a channel. |
| attributes | [reviewed] [scientific] |
| language | en |