An exact analytical solution for the second order slip-corrected Reynolds lubrication equation

Izvedena je opšta Rejnoldsova jednačina podmazivanja za uslove strujanja sa klizanjem primenom opštih graničnih uslova klizanja drugog reda i pokazano je da ona ima tačno analitičko rešenje. Rešenje je dobijeno tansformacijom zavisno promenljive što je dovelo do mogućnosti analitičkog proračuna raspodele pritiska i masenog protoka u mikroležaju. Na taj način, poređenjem sa datim analitičkim rešenjem omogućena je provera eksperimentalnih i numeričkih rezultata za strujanje gasa u mikroležajima.We derive a general slip-corrected compressible Reynolds lubrication equation, valid for any choice of the slip velocities, and show that it possesses the exact analytical solution. It is obtained by a suitable transformation of the dependent variable, and it yields both the pressure distribution in the bearing and the mass flow rate through it. It can be usefully applied for testing the other, experimental or numerical results obtained under the same or similar physical conditions, against this solution

The exact analytical solution for the gas lubricated bearing in the slip and continuum flow regime

The exact analytical solution for the compressible two-dimensional gas flow in the microbearing is presented. The general slip-corrected Reynolds lubrication equation is derived and it is shown that it possesses an exact analytical solution. It is obtained by a suitable transformation of the independent variable, and it provides the pressure distribution in the bearing as well as the mass flow rate through it. By neglecting the rarefaction effect, this solution is also applicable to the continuum gas flow in the bearing, which also does not exist in the open literature. The obtained analytical solution can be usefully applied for testing the other, experimental or numerical results

An exact analytical solution for the second order slip-corrected Reynolds lubrication equation

Izvedena je opšta Rejnoldsova jednačina podmazivanja za uslove strujanja sa klizanjem primenom opštih graničnih uslova klizanja drugog reda i pokazano je da ona ima tačno analitičko rešenje. Rešenje je dobijeno tansformacijom zavisno promenljive što je dovelo do mogućnosti analitičkog proračuna raspodele pritiska i masenog protoka u mikroležaju. Na taj način, poređenjem sa datim analitičkim rešenjem omogućena je provera eksperimentalnih i numeričkih rezultata za strujanje gasa u mikroležajima.We derive a general slip-corrected compressible Reynolds lubrication equation, valid for any choice of the slip velocities, and show that it possesses the exact analytical solution. It is obtained by a suitable transformation of the dependent variable, and it yields both the pressure distribution in the bearing and the mass flow rate through it. It can be usefully applied for testing the other, experimental or numerical results obtained under the same or similar physical conditions, against this solution

Heritage Awareness and Sustainability of Built Environment between Theory and Practice: An Insight from ERASMUS+ Project

The Erasmus+ project titled Enhancing of Heritage Awareness and Sustainability of Built Environment in Architectural and Urban Design Higher Education (HERSUS) is being realised within the Strategic Partnerships for higher education action type. Its realisation started in 2020 and ever since the project has been gradually implementing and proposing numerous activities in cooperation between the research, private, and public sector, hence targeting both local and regional support towards higher education and practical arena cooperation. The intention of this article is to present the results of the first six months of the project implementation and to highlight specific conclusions which can contribute to threefold perspectives – educational, practical, and policy framework and contextual condition

Studija projekta 'Optimizacija i standardizacija autohtone tehnologije sjeničkog sira sa zaštitom oznake porekla'

Investigations are based on use of natural potentials on the wide region of Sjenica-Pešter highlands. Certain parameters on selected locations are recorded (soil, vegetation, livestock production, technology of milk and cheese production). On selected locations, farms and processing capacities detail researches are carried out relating to soil, artificial and natural grasslands, reproductive and production potential of cattle and sheep, determination of genetic and non-genetic factors affecting milk traits, quantity and quality of milk, proteins, milk fat, lactose, etc., technological and microbiological traits of milk and cheese. Main objectives of this research and development project is to realize scientific -technological solutions in primary livestock production using our own scientific potentials in order to provide increased productivity, increased number of market farmers capable for competitive economy and production on domestic and foreign market with recognized final product with protected geographical origin, in other words - optimization and standardization of native technology of white cheese from Sjenica with protected brand and origin.Istraživanja su zasnovana na korišćenju prirodnih potencijala šireg regiona Sjeničko-pešterske visoravni. U okviru ovih istraživanja obavlja se snimanje i proučavanje određenih parametara na odabranim lokalitetima ( zemljište, vegetacija, stočarstvo, tehnologija mleka i sira). Na odabranim lokalitetima, farmama i preradjivačkim kapacitetima obavljaju se detaljna istraživanja, zemljišta, prirodnih i veštačkih travnjaka i livada, reproduktivnih i proizvodnih potencijala goveda i ovaca, determinacija genetskih i negenetskih faktora na svojstva mlečnosti, kvantitet i kvalitet mleka, proteini, mlečna mast, laktoza i dr.,tehnološka i mikrobiološka svojstva mleka i sira. Osnovni ciljevi ovog istraživačko-razvojnog projekta je da se korišćenjem sopstvenih naučnih potencijala dođe do naučno-tehnoloških rešenja u primarnoj stočarskoj proizvodnji, koja će obezbediti porast produktivnosti, povećanje robnih proizvođača osposobljenih za konkurentnu proizvodnju na domaćem i stranom tržištu sa prepoznatljivim finalnim proizvodom zaštićenog geografskog porekla, odnosno optimizaciju i standardizaciju autohtone tehnologije Sjeničkog sira sa zaštitom oznake porekla

Low mach number, high order rarefied gas flow in micro-channels

U radu se tretira izotermsko strujanje razređenog gasa u mikro-kanalima promenljivog poprečnog preseka. Pretpostavlja se da je odnos kvadrata Mahovog broja i Rejnoldsovog broja mali, tako da se inercioni članovi u osnovnim jednačinama mogu zanemariti, a uticaj viskoznosti je dominantan u celom preseku kanala. Koriste se granični uslovi klizanja gasa na zidu višeg reda i pokazuje da razređenost gasa dovodi do povećanja masenog protoka pri istom odnosu ulaznog i izlaznog pritiska.Isothermal rarefied gas flow in micro-channels of slowly varying cross section is treated in this paper. It is assumed that the ratio of the reference Mach number square and the reference Reynolds number is a small quantity, so that inertia can be neglected and the effect of viscosity is spread over the whole cross-section of the channel. Higher order slip boundary condition on the wall is used for the solution of governing equations. Gas rarefaction leads to increase of mass flow rate for the same inlet and outlet pressure ratio

Low mach number, high order rarefied gas flow in micro-channels

U radu se tretira izotermsko strujanje razređenog gasa u mikro-kanalima promenljivog poprečnog preseka. Pretpostavlja se da je odnos kvadrata Mahovog broja i Rejnoldsovog broja mali, tako da se inercioni članovi u osnovnim jednačinama mogu zanemariti, a uticaj viskoznosti je dominantan u celom preseku kanala. Koriste se granični uslovi klizanja gasa na zidu višeg reda i pokazuje da razređenost gasa dovodi do povećanja masenog protoka pri istom odnosu ulaznog i izlaznog pritiska.Isothermal rarefied gas flow in micro-channels of slowly varying cross section is treated in this paper. It is assumed that the ratio of the reference Mach number square and the reference Reynolds number is a small quantity, so that inertia can be neglected and the effect of viscosity is spread over the whole cross-section of the channel. Higher order slip boundary condition on the wall is used for the solution of governing equations. Gas rarefaction leads to increase of mass flow rate for the same inlet and outlet pressure ratio

One-dimensional analysis of compressible flow in solar chimney power plants

A novel theoretical approach for the calculation of the buoyancy driven air flow in all constitutive parts (entrance to collector, collector, turbines, collector-to-chimney transition section and chimney) of a solar chimney power plant is presented in the paper. It consists in the use of one-dimensional model of flow. The flow in the collector and the chimney is considered as compressible, while the flow in entrance to collector, turbines and collector-to-chimney transition section is treated as incompressible. Differential equations that describe the flow in the collector and in the chimney, together with algebraic equations that describe the flow in other parts of the plant are simultaneously solved. As a result, distribution of basic physical quantities, like velocity, temperature, pressure and density, in the collector and the chimney are obtained. The model is tested on two solar chimney power plants: well known Manzanares plant and Enviromission plant. The obtained results are in good agreement with measured results from Manzanares plant known in literature, together with predicted values of turbine power and turbine pressure drop for Enviromission plant. In addition, dimensional analysis of the model equations is performed and the results for mass flow rate, available turbine power, chimney height, etc. are presented. These results can be used as reliable prediction of the performance of solar chimney power plants

On the simultaneous effects of gas rarefaction, wall porosity, and inertia in microchannel flows

The superposition of two effects that cause the flow to slip over the walls of a microchannel: Gas rarefaction and wall porosity, is treated in the paper. At that, in order to account for moderately high values of the Reynolds number, observed in some experiments, the effect of inertia is included into the analysis as a second order effect. The approach is fully analytic and consists in the development of a simple perturbation scheme in which the Knudsen number plays the role of a unique small parameter. The obtained results are in qualitative agreement with experiments, and may be usefully applied for the design of aerostatic bearings in which a porous material is used as the flow restrictor

On the simultaneous effects of gas rarefaction, wall porosity, and inertia in microchannel flows

The superposition of two effects that cause the flow to slip over the walls of a microchannel: Gas rarefaction and wall porosity, is treated in the paper. At that, in order to account for moderately high values of the Reynolds number, observed in some experiments, the effect of inertia is included into the analysis as a second order effect. The approach is fully analytic and consists in the development of a simple perturbation scheme in which the Knudsen number plays the role of a unique small parameter. The obtained results are in qualitative agreement with experiments, and may be usefully applied for the design of aerostatic bearings in which a porous material is used as the flow restrictor