Predicition of groundwater level on Grohovo landslide using ruled based regression

In order to contribute to understanding the effect of atmospheric conditions on the groundwater level fluctuations on Grohovo landslide, a machine learning tool for induction of models in form of the set of rules was applied on a dataset comprising daily atmospheric and groundwater level data measured in 2012. The atmospheric data comprises of an average daily air temperature, humidity, wind speed, pressure, total evapotranspiration, and precipitations. For the experiment independent variables i.e. atmospheric data and present groundwater level were used to model target variable i.e. predicted groundwater level for 24 and 48 hours in advance. The presented models give predictions 24 (first model) and 48 (second model) hours in advance for groundwater level fluctuations on Grohovo landslide. The first model is consisted from seven, and the second model from five rules. Both models have very high correlation coefficients of 0.99 and 0.97, respectively. From the given models, it can be concluded that the most influence on the groundwater level fluctuations have sum of daily precipitations and average daily air temperature. The obtained models are intended for use in the models for debris flow propagation on the Rječina River as a part of an Early Warning System

Hydrodynamic Analysis of Fluid Obstruction Around Different Geometric Bodies

The aim of this paper is to conduct a hydrodynamic analysis of fluid flow around different geometric bodies on the laboratory physical model HM 133 of the Gunt Company from Hamburg and to show the formation of boundary layer and separation points on the observed bodies. The paper covers the field of real fluid dynamics which includes a description of laminar and turbulent flow together with a Reynolds number. A detailed representation of the boundary layer, its characteristics, and its structure are included. The body models in the paper used on the HM 133 physical model were an oblong straight body and cylindrical bodies with 6 mm, 12 mm, 18 mm, and 24 mm in diameter. The research was conducted in the Hydrotechnical Laboratory of the Faculty of Civil Engineering, University of Rijeka. Hydrodynamic analyses were made based on the tested body models on the physical model HM 133 together with the analyses on the numerical models performed using the ANSYS Fluent software

Experimental Determination of Dynamic And Kinematic Viscosity of Liquids

U ovom radu opisana su osnovna svojstva i značajke viskoznosti, prikazani su najčešći instrumenti i metode za određivanje koeficijenata dinamičke i kinematičke viskoznosti te je pojam viskoznosti sagledan kroz reološki dijagram. Na temelju viskozimetra s padajućom čeličnom kuglicom različitih promjera i masa, u hidrotehničkom laboratoriju Građevinskog fakulteta u Rijeci provedeno je laboratorijsko određivanje dinamičkog i kinematičkog koeficijenta viskoznosti na fizikalnom modelu na temelju 4 različite vrste kapljevina (voda iz gradskog vodoopskrbnog sustava, morska voda, suncokretovo ulje i mlijeko) u ovisnosti o promjeni temperature.This paper describes the basic properties and characteristics of viscosity and presents the most common instruments and methods for determining the dynamic and kinematic viscosity coefficients. Using a viscometer with a falling steel ball of different diameters and masses, in the hydrotechnical laboratory of the Faculty of Civil Engineering in Rijeka a laboratory determination of dynamic and kinematic viscosity coefficient was performed on physical model of 4 different types of liquids (drinking water, seawater, sunflower oil and milk) depending on the change in temperature

Physical Model of Water Seepage Through Porous Medium

U ovom radu opisana su osnovna načela i vladajuće jednadžbe za opis strujanja podzemne vode kroz porozni materijal. U svrhu dobivanja mjerodavnih vrijednosti pojedinih karakterističnih fizikalnih veličina kod strujanja podzemne vode u pjeskovitom poroznom materijalu (brzina procjeđivanja, ekvipotencijal u određenoj točki unutar prostora, hidraulički gradijenti, protok i sl.) korišten je fizikalni model GUNT HM169 koji čini sastavni dio hidrotehničkog laboratorija Građevinskog fakulteta Sveučilišta u Rijeci. U radu je opisan princip rada za navedeni fizikalni model te način pripreme samih eksperimentalnih pokusa. U tom pogledu, izrađeno je nekoliko hidrodinamičkih analiza strujanja podzemne vode u odnosu na varijabilnost potencijala gornje i donje vode, analiza strujanja ispod vertikalnog čeličnog žmurja (dijafragme) te analiza opstrujavanja podzemne vode ispod prostorno trapezno izmodelirane prirodne nasute brane. Za potrebe provođenja pokusa, nasuta brana ručno je izrađena od pleksi stakla. Svrha istraživanja kroz fizikalni model HM169 bila je dobivanje jasnije slike strujnog polja ispod pojedinih hidrotehničkih objekata i, posljedično, dobivanje simulacijskih prikaza propagacije toka podzemne vode koja je praćena žutim fluorescin traserom.This paper describes basic principles and governing equations for describing groundwater flow through porous material. In order to obtain the relevant values of some of the characteristic physical quantities of groundwater flow in the sandy porous material (infiltration velocity, equipotential at a certain point within the space, hydraulic gradients, flow, etc.), the physical model GUNT HM169 was used, which is an integral part of the hydro technical laboratory of the Faculty of Civil Engineering, University of Rijeka. The paper describes the working principle for the mentioned physical model and the preparation of the experimental trials themselves. In this respect, several hydrodynamic analyzes of groundwater flow regarding the upper and lower water variability potential were made as well as the flow analysis below the vertical steel diaphragm and the analysis of groundwater depletion under the spatially trapezoidal modified natural sloping dam. To carry out the experiment, the sloping dam was manually made of Plexiglas. The purpose of the research through the physical model HM169 was to obtain a clearer picture of the streamline field below the individual hydroelectric objects and consequently to obtain a simulation of the propagation of the groundwater flow which was followed by a yellow fluorescence tracer

Computational Fluid Dynamics and Fluid Flow Visualization Methods

U ovom radu obrađena je tematika primjene i svrhe Računalne dinamike fluida (RDF) u svakodnevnoj praksi te metode vizualizacije strujanja fluida. Radi lakšeg shvaćanja pojma modela turbulencije u radu su navedene osnovne karakteristike fluida od kojih je fokus dan na viskoznosti i kompresibilnosti. U svrhu opisa dinamike gibanja fluida definirane su osnovne vladajuće jednadžbe strujanja fluida, koje uključuju laminarani i turbulentni režim toka. Značajan fokus ovog rada posvećen je kreiranju numeričkih modela primjenom Računalne dinamike fluida, od samog predprocesiranja, definiranja domene problema, izrade numeričke mreže, sve do parametara potrebnih za definiranje pojedinih turbulentnih modela te načina vizualizacije rješenja promatranog problema kroz postprocesiranje. Drugi dio rada razmatra eksperimentalne i računalne metode vizualizacije strujanja fluida unutar kojih su dani pojedini primjeri za svaku od metoda vizualizacije.This paper deals with application and purpose of Computational Fluid Dynamics (CFD) in everyday practice and methods of fluid flow visualization. In order to facilitate the understanding of the concept of turbulence model the paper presents the basic characteristics of the fluid, of which the focus is on viscosity and compressibility. For the purpose of describing the dynamics of fluid motion, the basic governing equations of fluid flow are defined, which include laminar and turbulent flow regimes. A significant focus of this paper is given to the creation of numerical models using CFD, from preprocessing, defining the problem domain, creating a numerical network, to necessary parameters for defining individual turbulent models and methods of visualizing the solution of the observed problem through postprocessing. The second part of the paper discusses experimental and computational methods of fluid flow visualization, within which individual examples for each of the visualization methods are given

The Origin of Water And Its Meaning for Planet Earth

U radu je dan opis podrijetla vode na planeti Zemlji i njezino značenje u prošlosti i sadašnjosti. Analizirani su razmjeri kretanja vode na zemlji, njihove značajke, kao i glavni izvori dostupne vode na zemlji izraženi kroz postotni udio na globalnoj razini. Također je razmatran nastanak vode u Svemiru i proizvodnja kisika u ranoj fazi nastanka planeta. Fokus rada bazira se na održanju kvalitete vode dostupne na Zemlji te pojavi globalne varijabilnosti intenziteta oborina koje u zadnjih nekoliko desetljeća mijenjaju značajke velikih svjetskih površina kroz procese velikih suša i poplava. Kroz rad su opisani neki od najznačajnijih primjera eksploatacije pitkih voda u svijetu kroz površinske i podzemne rezerve vode. Analizirane su mogućnosti povećanja proizvodnje hrane za ljudske potrebe u pogledu povećanja zemljišta kroz tehnološki napredne metode te zaštita vodnih resursa uslijed klimatskih promjena. Dan je osvrt na značajke kvalitete prirodne vode u medicini i industriji, poboljšanje sanitarnih uvjeta, utjecaj ljudskog zagađenje na globalnoj razini, gospodarski rast i problem smanjenja vode, kao i globalni problem ispuštanja nepročišćenih otpadnih voda u recipijente i, posljedično, ugrožavanje flore i faune.This paper gives a description of the origin of water on planet Earth and its importance in the past and the present. The paper presents the analysis of water flow extent on Earth, its characteristics, as well as the main sources of available water on the planet, expressed through a percentage share on a global scale. It also deals with the origin of water in the Universe, as well as the production of oxygen at the early stages of the planet’s formation. The focus of the paper is based on maintaining the quality of water available on Earth and the global variability of precipitation intensity that has changed the characteristics of large world surfaces through significant drought and flood processes over the last decades. Throughout the paper, some of the most important examples of exploitation of drinking water in the world through the surface and underground reserves of water are described. The possibilities of increasing the production of food for human needs in terms of increasing land through technologically advanced methods and the protection of water resources due to climate change are analyzed. At the end of the paper, there is a review of the characteristics of natural water quality in medicine and industry, sanitary conditions improvement, the impact of global pollution on human beings, economic growth and the problem of water scarcity, as well as the global problem of discharging untreated wastewater into the recipients and consequently endangering flora and fauna

Experimental Determination of Capillarity of Certain Liquids

U radu su opisane osnovne karakteristike kapilarnosti kao jedne od osnovnih svojstva kapljevina. Definiran je pojam površinskog naprezanja, značajke kohezijskih i adhezijskih sila unutar kapljevine, način određivanja visine kapilarnog dizanja te najznačajnije metode za mjerenje kapilarnosti u praksi. Drugi dio rada baziran je na izradi eksperimentalnih pokusa u hidrotehničkom laboratoriju Građevinskog fakulteta u Rijeci. Prvi pokus je obuhvatio eksperimentalna mjerenja visina kapilarnog dizanja kapljevine između dviju staklenih pločica, a drugi određivanje visina kapilarnog dizanja kapljevine u malim uskim cjevčicama različitih promjera za četiri različite vrste kapljevina pri njihovim različitim temperaturama.The paper describes the basic characteristics of capillarity as one of the basic properties of liquids. The concept of surface tension, the characteristics of cohesion and adhesion forces, the method of determining the height of capillary rise and the most important methods for measuring capillarity in practice are defined. The second part of the paper is based on the creation of an experiments in the Hydrotechnical laboratory of the Faculty of Civil Engineering in Rijeka. The first experiment included experimental measurements of liquid rise heights between two glass plates and the second one was determination of liquid rise heights in small narrow tubes of different diameters for four different types of liquids at their different temperatures