1. Computational modeling of natural convection in nanofluid-saturated porous media: an investigation into heat transfer phenomena : Janja Kramer Stajnko ... [et al.]Janja Kramer Stajnko, Jure Ravnik, Renata Jecl, Matjaž P. Nekrep, 2024, original scientific article Abstract: A numerical study was carried out to analyze the phenomenon of natural convection in a porous medium saturated with nanofluid. In the study, the boundary element method was used for computational modeling. The fluid flow through a porous matrix is described using the Darcy– Brinkman–Forchheimer momentum equation. In addition, a mathematical model for nanofluids was used, which follows a single-phase approach and assumes that the nanoparticles within a fluid can be treated as an independent fluid with effective properties. A combination of single- and sub-domain boundary element methods was used to solve the relevant set of partial differential equations. The method was originally developed for pure flow scenarios, but also proves to be effective in the context of fluid flow through porous media. The results are calculated for the case of two- and three-dimensional square cavities. In addition to various values of dimensionless control parameters, including the porous Rayleigh number (Rap), Darcy number (Da), porosity (ϕ) and nanoparticle volume fractions (φ), the effects of the inclination angle of the cavity on the overall heat transfer (expressed by the Nusselt number (Nu)) and fluid flow characteristics were investigated. The results indicate a pronounced dependence of the overall heat transfer on the introduction of nanoparticles and inclination angle. The heat transfer in a two-dimensional cavity is increased for higher values of Darcy number in the conduction flow regime, while it is suppressed for lower values of Darcy number in the Darcy flow regime. In the case of a three-dimensional cavity, increasing the volume fraction of nanoparticles leads to a decrease in heat transfer, and furthermore, increasing the inclination angle of the cavity considerably weakens the buoyancy flow
Keywords: porous media, nanofluids, natural convection, boundary element method
Published in DKUM: 10.01.2025; Views: 0; Downloads: 4
 Full text (7,40 MB)
This document has many files! More... |
2. Advances in monitoring and understanding the dynamics of suspended-sediment transport in the river Drava, Slovenia: an analysis more than a decade-longJanja Kramer Stajnko, Renata Jecl, Matjaž P. Nekrep, 2023, original scientific article Abstract: Managing sediment transport in streams is crucial to the surface water resource development strategy and has several implications for flood risk and water management, hydropower use, and balancing river morphology. This paper summarises the movement and behaviour of suspended sediment within the Slovenian portion of the River Drava, covering a span of thirteen years from 2005 to 2018. An analysis of relevant data collected during this period is also presented. Suspended-sediment dynamics strongly depend on flow velocity, seasonal variations in sediment sources, and human interventions in the riverbed. The transportation of material in the River Drava results in the accumulation of sediments in reservoirs and riverbeds, consequently impeding the natural hydrological cycle by reducing the outflow into aquifers. The 2018 high-water event is analysed in terms of the dependence of concentration of suspended sediments on discharge, where counterclockwise hysteresis was observed, providing an essential clue to the origin of sediment. Sediments from the River Drava in Slovenia are managed with some conventional processes and are mainly deposited or reintegrated into rivers and aquatic ecosystems. Some additional sediment management strategies with long-term solutions for efficient and comprehensive water management, hydropower, and ecological problems are proposed.
Keywords: sediment transport, streams, suspended sediment dynamics, suspended sediment transport, river Drava, sediment management, monitoring, water management
Published in DKUM: 13.09.2023; Views: 476; Downloads: 43
Full text (4,52 MB)
This document has many files! More... |
3. Double diffusive natural convection in a horizontal porous layer with the boundary domain integral methodRenata Jecl, Janja Kramer Stajnko, Leopold Škerget, 2009, original scientific article Abstract: We present the boundary-domain integral method, one of the numerical methods for solving the transport phenomena in porous media. The results for the case of double diffusive natural convection in a porous horizontal layer, which is fully saturated with an incompressible fluid, are obtained. Modified Navier-Stokes equations were used to describe the fluid motion in porous media in the form of conservation laws for mass, momentum, energy and species. Several results for different cases of double diffusive natural convection in a porous horizontal layer are presented and compared with some published studies in which calculations with other numerical methods were performed.
Keywords: porous media, boundary domain integral method, double diffusive natural convection, Darcy-Brinkman equation
Published in DKUM: 06.06.2018; Views: 1197; Downloads: 70
Full text (454,56 KB)
This document has many files! More... |
4. PROBLEMATIKA ZAGOTAVLJANJA POŽARNE OSKRBE V VODOVODNIH OMREŽJIH NA OBMOČJU RAZPRŠENE POSELITVEBojan Štesl, 2016, undergraduate thesis Abstract: Diplomska naloga »Problematika zagotavljanja požarne oskrbe v vodovodnih omrežjih na območju razpršene poselitve« predstavlja strokovno analizo izgradnje predvidenega vodovodnega omrežja in objektov, s katerimi se v vodovodnem omrežju zagotovi zadostna količina vode za požarno oskrbo. Z njo želimo prikazati možnost izboljšav ureditve vodovodnega omrežja, ki so nujno potrebne že v fazi načrtovanja vodovodnega omrežja, kjer je potrebno na podlagi strokovnih osnov, potreb ter zahtev investitorjev zagotoviti racionalno in funkcionalno omrežje.
Keywords: vodovod, oskrba z vodo, projektiranje vodovoda in objektov, požarna voda, požarna zaščita
Published in DKUM: 17.10.2016; Views: 1500; Downloads: 130
Full text (4,61 MB) |
5. |
6. MOŽNOSTI UMETNEGA ZASNEŽEVANJA NA SMUČIŠČU GOLTEAna Podkrižnik, 2016, undergraduate thesis Abstract: V diplomski nalogi so predstavljene možnosti zajetij tehnoloških voda, ki jih bomo uporabili za umetno zasneževanje smučarskih prog na smučišču Golte d.o.o. Diplomsko delo temelji na že pridobljenih meritvah in podatkih za izračun potrebnih vodnih črpalk. Na podlagi meritev, izračuna porabe tehnološke vode in primerjave z ustaljeno prakso drugod smo podali predlog za eno izmed podanih možnosti shranjevanja vode.
Cilj naloge je, da na podlagi primerjave možne izvedljivosti in ekonomičnosti variant določimo optimalen način napeljave vodovodnega sistema zasneževanja, ki bo izveden po zakonskih predpisih.
Keywords: vodovodni sistem, umetno zasneževanje, črpalke, akumulacijsko jezero, Krajinski park Golte, Natura 2000
Published in DKUM: 07.09.2016; Views: 1538; Downloads: 136
Full text (5,74 MB) |
7. Analiza dinamike transporta lebdečih plavin v rekah Drava in MuraMatjaž P. Nekrep, Janja Kramer Stajnko, Gregor Podlogar, Renata Jecl, 2012, professional article Abstract: V okviru mednarodnega projekta Čezmejna vodarska iniciativa za reki Drava in Mura (Drava- Mura Crossborder Initiative) - DRA-MUR-CI, na območjih obeh rek v državah Slovenija in Avstrija potekajo številne aktivnosti, ki vzpodbujajo sodelovanje obeh sodelujočih držav na področju razvoja in ukrepov za podporo in zaščito ljudi ter okolja pred naravnimi nesrečami, kot tudi izboljšanju življenjskega okolja ljudi, flore in favne. Raziskovalci s Fakultete za gradbeništvo Univerze v Mariboru se vključujemo v raziskave v okviru delovnega sklopa, ki pokriva področje transporta sedimentov s ciljem, da se vzpostavi učinkovit model lebdečih plavin, ki bo uporaben predvsem za kalibracijo modela sedimentov rek kot osnovo za njihovo nadaljnjo upravljanje.
Keywords: Drava, Mura, meritve pretokov, lebdeče plavine
Published in DKUM: 10.07.2015; Views: 1727; Downloads: 92
 Link to full text |
8. DRA-MUR-CI v oblakuMatjaž P. Nekrep, Janja Kramer Stajnko, Gregor Podlogar, Renata Jecl, 2012, published scientific conference contribution Abstract: V prispevku opisujemo predvsem informacijsko ter komunikacijsko podporo tistemu delu projekta DraMurCi, ki se ukvarja z spremljanjem lebdečih plavin. Reka povezuje več držav, prav tako pri delu na projektu sodelujemo strokovnjaki iz različnih ustanov sodelujočih držav. Viri podatkov in rezultati meritev so raznoliki (stalna merilna mesta, spletni strežniki, terenske meritve, ..) ter podatkovno in geografsko zelo razpršeni. Rešitev zbiranja ter urejanja vseh teh podatkov v oblaku je bila tako skorajda samoumevna. Zaradi lažje in neomejene (časovno, krajevno, neodvisnost od naprav) dostopnosti do rezultatov obdelav smo se odločili, da tudi modele razvijemo in poganjamo v oblaku ter tako omogočimo od strojne opreme ter časa in kraja neodvisno delovanje modelov ter dostop do rezultatov.
Keywords: lebdeče plavine, programska oprema
Published in DKUM: 10.07.2015; Views: 1676; Downloads: 67
Link to full text |
9. Interdiscpilinarna [!] meritev prenosa suspendiranih trdnih delcev v izbranih profilih na rekah Dravi in Muri (projekt DRA-MUR-CI)Ludvik Trauner, Bojana Dolinar, Renata Jecl, Matjaž P. Nekrep, Janja Kramer Stajnko, Gregor Podlogar, Boštjan Kovačič, Rok Kamnik, 2012, published scientific conference contribution Abstract: V okviru bilateralnega projekta DRA-MUR-CI med Slovenijo in Avstrijo (Čezmejna vodarska iniciativa za reki Drava in Mura) potekajo meritve koncentracije in sestave suspendiranega materiala, ki ga obe reki prenašata na svoji poti. Na izbranih prečnih prerezih se v določenih časovnih obdobjih opravijo različne primerjalne meritve ter analiza vzorcev. Interdisciplinarne meritve izvajajo strokovnjaki s področja geotehnike, hidrotehnike in geodezije. V prispevku so podani izbrani rezultati meritev na dveh prečnih profilih reke Drave in enem profilu reke Mure. Prikazane so sočasne vrednosti za parametre, kot so: izmerjene vrednosti pretokov in hitrosti vode ter koncentracije z analizo sestave suspendiranih trdnih delcev. Na osnovi teh vrednosti je na FG UM razvit inovativni model za simulacijo prenosa suspendiranih trdnih delcev v izbranih profilih na obeh rekah. Rezultati prikazanega raziskovalnega projekta DRA-MUR-CI (2009-2013) predstavljajo uspešno nadaljevanje predhodnih raziskovalnih del v okviru večih projektov: WRM-Knet Water (2005-2010), RIP Kostak (2006-2007), HE Boštanj (2007-2009), ČHE Kozjak (2007-2009) in omogočajo z nadaljevanjem raziskovanj zanesljivo določanje in simuliranje časovno odvisne obtežbe s suspendiranimi materiali in bilance le-teh na celotni trasi obeh rek.
Keywords: hidrologija, geodetske meritve, geotehnika, suspendirani material, lebdeče plavine
Published in DKUM: 10.07.2015; Views: 1431; Downloads: 69
Link to full text |
10. ČIŠČENJE ODPADNIH VODA V MALIH KOMUNALNIH ČISTILNIH NAPRAVAH ZMOGLJIVOSTI DO 50 PEMateja Žerjav, 2015, undergraduate thesis Abstract: Republika Slovenija je z vstopom v Evropsko unijo sprejela njene direktive in jih prenesla na svojo zakonodajo. Operativni program odvajanja in čiščenja komunalne odpadne vode (novelacija za obdobje od leta 2005 do leta 2017) je bistvenega pomena. Ta zahteva za posamezne objekte, ki ne bodo vključeni v javni kanalizacijski sistem, odvajanje v male komunalne čistilne naprave, najkasneje do konca leta 2017. V diplomskem delu je obravnavana zakonodaja na tem področju, primerne tehnologije čiščenja in obveznosti uporabnikov malih komunalnih čistilnih naprav zmogljivosti do 50 populacijskih enot. Del diplomske naloge je namenjen dejavnikom, ki jih je priporočljivo upoštevati pri izbiri male komunalne čistilne naprave.
Keywords: gradbeništvo, komunalna odpadna voda, mala komunalna čistilna naprava, Operativni program odvajanja in čiščenja komunalne odpadne vode, biološke čistilne naprave, rastlinske čistilne naprave
Published in DKUM: 26.03.2015; Views: 2521; Downloads: 602
Full text (2,30 MB) |
