59 research outputs found
Stepped spillway flow: Comparison of numerical and scale models
Tema rada je modeliranje strujnog polja na stepenastom brzotoku brane Bogovina. Analiza je sprovedena na rezultatima dobijenih pomoÄu: fiziÄkog modela, empirijskih jednaÄina i numeriÄkog modela. Slaganja rezultata empirijskih jednaÄina i numeriÄkog modela su u prihvatljivim granicama, dok je primeÄeno njihovo znaÄajno odstupanje od rezultata merenja na fiziÄkom modelu. Uzrok ovih razlika je proces samo-aeracije mlaza. BuduÄi da je ovaj proces važan za ovaj vid strujanja, nepohodno je poboljÅ”ati postojeÄe empirijske zavisnosti i numeriÄke modele.This paper deals with flow modelling of the stepped spillway for the Bogovina dam. The analysis was conducted using three approaches: scalemodelling, empirical equations and numerical modelling. An acceptable agreement was achieved between the empirical equations and the numerical model results, while both of them exhibit considerable differences when compared to scale-model. These discrepancies can be contributed to the difficulties in modelling the process of air-entrainment. Since air-entrainment is important for providing good estimates, existing empirical equations as well as numerical models require further improvements
Analiza nekih uticaja na životnu sredinu izgradnje mosta na Adi
Construction of the new cable stayed bridge on the Sava River in Belgrade - the 'Ada Bridge', required extensive foundation works at the entrance of the Ada Bay, with two environmentally unfavourable consequences -increased siltation of the Bay entrance, and dislodgement of protected bird species (the pygmy cormorant). This paper deals with actions undertaken in order to resolve these unfavourable environmental impacts. Numerical 2D flow simulations were done in order to design a reconstructed Bay entrance with reduced siltation, and to shape the existing sand bars to become, after backfilling and planting, a renewed habitat for the protected bird species.Izgradnja Mosta na Adi iziskivala je obimne radove na ulazu u ÄukariÄki zaliv, sa dva nepovoljna uticaja po životnu sredinu - poveÄano zasipanje ulaza u Zaliv i proterivanje zaÅ”tiÄene ptiÄje vrste - 'malog vranca', sa njegovog staniÅ”ta na Å”picu Ade. Ovaj Älanak opisuje aktivnosti na otklanjanju ovih nepoželjnih uticaja. Na osnovu proraÄuna kapaciteta unoÅ”enja i istaložavanja reÄnog nanosa na ulazu u Zaliv, projektovano je takvo ureÄenje obala koje istovremeno zadovoljava odreÄene uslove u pogledu režima strujanja vode i nanosa, ornitoloÅ”ke uslove obnove staniÅ”ta, kao i estetske uslove regulacije obale oko pilona mosta
Rekonstrukcija hidrograma na vodomernim stanicama primenom rezultata asimilacije preliminarni rezultati
Održivo upravljanje vodnim resursima zahteva prognoze dostupne koliÄine vode kao pomoÄ u donoÅ”enju upravljaÄkih odluka. MeÄutim, te prognoze su Äesto nepouzdane zbog prisustva razliÄitih tipova neodreÄenosti. Kod primene linijskih (1D) modela teÄenja u otvorenim tokovima neki od dominantnijh izvora neodreÄenosti su nedovoljno dobro poznavanje graniÄnih uslova (hidrogrami dotoka, krive protoka) i nepouzdani poÄetni uslovi koji su osnova od koje se zapoÄinje prognoza. Kontinulana merenja na sistemu (npr. merenja nivoa na reci) predstavljaju relativno pouzdan reprezent njegovog stanja ali pokrivaju samo jedan mali deo domena koji se razmatra. Zbog toga se pribegava postupku asimilacije podataka kojom se usaglaÅ”avaju rezultati 1D modela teÄenja u reci i merenja nivoa. Ova usaglaÅ”avanja se sprovode za veÄ prikupljene podatke, u vremenskom periodu neposredno pre trenutka od koga se želi izvrÅ”iti prognoza. Na kraju asimilacionog perioda model bolje oslikava trenutno stanje na celom domenu i može se iskoristiti za prognozu. MeÄutim, ako se radi kontinualna asimilacija modela, promene u stanju tokom asimilacije ukazuju na stepen greÅ”ke u ulaznim hidrogramima. Ovo istraživanje prikazuje potencijal nove metode za asimilaciju podataka za rekonstrukciju stvarnih hidrograma na vodomernim stanicama na osnovu zabeleženih nivoa. Ovaj postupak se može koristiti kao alat za rekonstrukciju poplavnih talasa i za procenu krivih protoka na pojedinim lokacijama
Ski odskok sa horizontalnim skretanjem mlaza
Ski odskok je āstandardno rjeÅ”enjeā, kada je u pitanju evakuacija velikih voda kod visokih brana. PomoÄu ski odskoka omoguÄeno je da se gubi odreÄeni dio energije, prije nego mlaz udari u donju vodu. Da bi se omoguÄila veÄa aeracija mlaza i efikasnije rasipanje energije, kao rjeÅ”enje se preporuÄuje ski odskok sa horizontalnim skretanjem mlaza. Pored povoljnih geoloÅ”kih prilika neophodnih za primjenu ovog rjeÅ”enja za preporuku je svakako provjera rasporeda dinamiÄkih pritisaka duž kaÅ”ike kao i dometa mlaza ski odskoka. Sve ove karakteristike neophodno je provjeriti na hidrauliÄkom modelu. U ovom radu se daje prikaz primjene ski odskoka sa horizontalnim skretanjem mlaza na brani HE Zavoj kod Pirota, za koja su sprovedena hidrauliÄka modelska ispitivanja
Analiza nekih uticaja na životnu sredinu izgradnje mosta na Adi
Construction of the new cable stayed bridge on the Sava River in Belgrade - the 'Ada Bridge', required extensive foundation works at the entrance of the Ada Bay, with two environmentally unfavourable consequences -increased siltation of the Bay entrance, and dislodgement of protected bird species (the pygmy cormorant). This paper deals with actions undertaken in order to resolve these unfavourable environmental impacts. Numerical 2D flow simulations were done in order to design a reconstructed Bay entrance with reduced siltation, and to shape the existing sand bars to become, after backfilling and planting, a renewed habitat for the protected bird species.Izgradnja Mosta na Adi iziskivala je obimne radove na ulazu u ÄukariÄki zaliv, sa dva nepovoljna uticaja po životnu sredinu - poveÄano zasipanje ulaza u Zaliv i proterivanje zaÅ”tiÄene ptiÄje vrste - 'malog vranca', sa njegovog staniÅ”ta na Å”picu Ade. Ovaj Älanak opisuje aktivnosti na otklanjanju ovih nepoželjnih uticaja. Na osnovu proraÄuna kapaciteta unoÅ”enja i istaložavanja reÄnog nanosa na ulazu u Zaliv, projektovano je takvo ureÄenje obala koje istovremeno zadovoljava odreÄene uslove u pogledu režima strujanja vode i nanosa, ornitoloÅ”ke uslove obnove staniÅ”ta, kao i estetske uslove regulacije obale oko pilona mosta
Geologically-Driven Migration of Landmines and Explosive Remnants of WarāA Feature Focusing on the Western Balkans
Landmines and explosive remnants of war are still present in the Western Balkans and remain a deadly legacy of the hostilities at the end of the 20th century. Over the years, several incidents have occurred in Bosnia and Herzegovina, in Serbia, and in Croatia where intact ordnance has caused injuries and fatalities. Floods, torrential flows, and gravitational mass movements pose a particular threat. Landmines and explosive remnants of war are mobilized and displaced into previously uncontaminated areas. We first discuss the historical and technical background of this hazardous situation. We then show which hydro-morphological processes are responsible for the mobilization and displacement. We then illustrate how a prediction of the likely contaminated areas can be obtained. We show that the problem can only be tackled using a stochastic-deterministic model. However, for the eventual development of risk-hazard maps, preliminary work using laboratory experiments and field surveys is required. The article, therefore, proposes a novel approach to the problem in an international research project. The aim would be to produce risk-hazard maps that can be used by elected decision-makers, administrative authorities, and emergency personnel in affected municipalities
Modeliranje kvaliteta vode u zalivu primenom modela ravanskog teÄenja
Contamination of river waters in terms of scale, intensity, and duration cause such severe problems that application of conventional engineering methods for environmental remediation projects is no longer adequate, and much more thorough hydraulic analysis, based on Computational Hydraulics, is required. Possibilities of such an approach are illustrated by a case study remediation of the Cukarica Bay on the Sava River in Belgrade. Measures, such as flushing of the Bay, have been studied by numerical simulations, using two-dimensional finite-element model. By studying physical processes in detail, it was possible to draw many useful conclusions, and to make appropriate recommendations to investors and working operative.ZagaÄenje voda stvara tako ozbiljne probleme da primena standardnih inženjerskih metoda u projektima zaÅ”tite životne sredine viÅ”e nije opravdana. Ovakvi projekti zahtevaju primenu novih alata i metoda baziranih na numeriÄkim modelima. U ovom radu je prikazan rezultat simulacije kvaliteta vode na primeru ÄukariÄkog zaliva na reci Savi u Beogradu. Primena mera Äiji je cilj poboljÅ”anje kvaliteta vode, kao Å”to je ispiranje zaliva, ispitana je pomoÄu modela ravanskog teÄenja baziranog na metodi konaÄnih elemenata. Sagledavanjem uticaja predloženih mera moguÄe je dati odgovarajuÄe preporuke investitorima i izvoÄaÄima radova
Modeliranje kvaliteta vode u zalivu primenom modela ravanskog teÄenja
Contamination of river waters in terms of scale, intensity, and duration cause such severe problems that application of conventional engineering methods for environmental remediation projects is no longer adequate, and much more thorough hydraulic analysis, based on Computational Hydraulics, is required. Possibilities of such an approach are illustrated by a case study remediation of the Cukarica Bay on the Sava River in Belgrade. Measures, such as flushing of the Bay, have been studied by numerical simulations, using two-dimensional finite-element model. By studying physical processes in detail, it was possible to draw many useful conclusions, and to make appropriate recommendations to investors and working operative.ZagaÄenje voda stvara tako ozbiljne probleme da primena standardnih inženjerskih metoda u projektima zaÅ”tite životne sredine viÅ”e nije opravdana. Ovakvi projekti zahtevaju primenu novih alata i metoda baziranih na numeriÄkim modelima. U ovom radu je prikazan rezultat simulacije kvaliteta vode na primeru ÄukariÄkog zaliva na reci Savi u Beogradu. Primena mera Äiji je cilj poboljÅ”anje kvaliteta vode, kao Å”to je ispiranje zaliva, ispitana je pomoÄu modela ravanskog teÄenja baziranog na metodi konaÄnih elemenata. Sagledavanjem uticaja predloženih mera moguÄe je dati odgovarajuÄe preporuke investitorima i izvoÄaÄima radova
NumeriÄka simulacija koncentrisanog ispuÅ”tanja izbagerovanog nanosa u maticu reke
This paper deals with prediction of hydraulic consequences of concentrated release of dredged sediments into the river using a two-dimensional numerical model. It is shown that flow, concentration, and siltation fields can be efficiently simulated by the numerical model. A special concern is given to the problem of the numerical model calibration. For illustration, results pertaining to the concentrated release of sediment dredged from the Äukarica Bay into the Sava River, are presented.Ovaj rad govori o moguÄnostima predviÄanja hidrauliÄkih posledica koncentrisanog ispuÅ”tanja izbagerovanog materijala u maticu reke pomoÄu numeriÄkog modela ravanskog teÄenja. Pokazuje se da se numeriÄkim simulacijama može efikasno reprodukovati strujno polje, raspored koncentracije i raspored zasipanja u reÄnom koritu. Posebno je razmotren problem kalibracije modela. Kao primer, prikazani su rezultati koji se odnose na koncentrisano ispuÅ”tanje nanosa izbagerovanog iz ÄukariÄkog zaliva u maticu reke Save
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