Ing - Civ (Mag.)(ord. 270) - MI (488) INGEGNERIA CIVILE - CIVIL ENGINEERING

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A

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056814 - NUMERICAL FLUIDS LAB

057000 - FLUIDS LABS

Ing Ind - Inf (Mag.)(ord. 270) - MI (487) MATHEMATICAL ENGINEERING - INGEGNERIA MATEMATICA

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A

ZZZZ

057000 - FLUIDS LABS

095962 - FLUIDS LABS

095962 - FLUIDS LABS

Obiettivi dell'insegnamento

The course aims at training master students in the analysis of fluid dynamic processes from different perspectives. Students learn to handle a variety of techniques in order to capture and model the complexity of fluid dynamic phenomena: theoretical approaches, numerical modelling, experimental testing. Students are asked to combine information with different nature (theoretical vs. heuristic) and origin (numerical/theoretical vs. experimental), with the aim of understanding the physics of fluid flow processes and its engineering handling.

Risultati di apprendimento attesi

Knowledge and ability in understanding:

recognize and describe basic features of internal and external flows, for both laminar and turbulent regimes

know a variety of theoretical and heuristic models in fluid dynamics

understand the role of closure models

Ability in applying knowledge and understanding:

make use of statistical tools in data analysis

make use of numerical tools for solving differential models in fluid mechanics

apply a variety of models for the investigation of simple yet engineering-relevant fluid dynamics processes

phenomenological analysis of relevant processes in fluid dynamics

Making judgments:

choose adequate model for fluid dynamic processes

evaluate uncertainties in experimental results

evaluate the physical consistency of the numerical solution

evaluate uncertainties in numerical modelling

Argomenti trattati

The course comprises theoretical, numerical and experimental analyses of a variety of fluid flows.

The THEORETICAL BACKGROUND is offered through the following modules:

1) equations governing flow flows

basic concepts of continuum mechanics

physical properties of fluids: density; vapor tension and cavitation; coefficients of compressibility; viscosity and rheology; surface tension

fluid statics

kinematics:Eulerian and Lagrangian frameworks; material derivative; streamlines and pathlines; rate of strain tensor and rigid rotation tensor

mass conservation equation in differential and integral formulations

momentum conservation equation in differential and integral formulations

inviscid flows: the Euler equations; the Bernoulli theorem; irrotational flows and potential flows

the Navier-Stokes equations for viscous, Newtonian flows in differential, integral, and dimensionless formulations

2) modelling of turbulent flows

basic elements of turbulence

basic approach in turbulence modelling: DNS, LES, (U)-RANS

(U)-RANS-based modelling of turbulence: the eddy-viscosity assumption and the k-epsilon standard turbulence model. Brief outline of other eddy-viscosity based models and Reynolds stresses models.

3) boundary layer theory

boundary layer formulation of the Navier-Stokes and RANS equations

boundary layer theory of internal flow: channel flow and circular pipe flows

boundary layer of external flows: flows over a flat plate and cylinder/sphere.

4) forces exerted on solid objects in a fluid flow

brief outline of the Buckingham theorem and dimensionless quantities

concepts of drag and lift force

functional relations for the drag and lift coefficients: flat plate and cylinder/sphere. Unsteady effects and the Strouhal number

Goal of NUMERICAL LABORATORIES is to introduce the students to the correct use of Computational Fluid Dynamics (CFD) codes for engineering applications. In this perspective, the focus is not so much on solution algorithms and implementation-related issues but, rather, on the best practices and guidelines which must be followed to obtain reliable CFD predictions. Particular attention will be given to the concepts of benchmarking, calibration, and validation, as well as to convergence assessment, grid independence, and critical evaluation of the physical consistency of the simulation output. A deep discussion is made around the sources of uncertainty of the CFD solution, especially in relation to the modelling of turbulence in the RANS framework. CFD simulations of benchmark yet engineering-relevant configurations are performed and post-processed by the students as single or in small groups under the step-by-step guidance of the teachers. These tests cases include the flow in channels and/or pipes, the development of the boundary layer over a flat plate, and the unconfined flow around a circular cylinder.

In the EXPERIMENTAL LABORATORIES, the fluid mechanics processes are analyzed on laboratory measurements. An introduction to commonly used instrumentation in experimental fluid mechanics is provided, including a detailed discussion around the process of calibration and a few notes on basic concepts on data acquisition and processing. Videos of laboratory experiments will be shown, and the experimental data will be provided to the students, who will analyze and process them as single or in small groups under the step-by-step guidance of the teachers. Quantities measured or provided include velocity/pressure/forces/displacements.

The course deals with advanced fluid mechanics combining a scienifically rigourous methodology with an application-oriented vision. Given the importance of fluid dynamic processes in several engineering fields, the course provides knowledge and tools which can be used to gain more sustainable industrialization and foster innovation.

Prerequisiti

Fundamentals of continuum mechanics. Fundamentals of statistics. Fundamentals of numerical analysis.

Modalità di valutazione

The exam consists of a written test, mainly focused on the theoretical part of the course. By answering the written questions, which might also include simple exercises, the students demonstrate knowledge of the theoretical contents, competence on fluid mechanics processes as well as critical reasoning skills by discussing various fluid mechanics phenomena. Upon positive evaluation of the written test, an oral colloquium will take place, which will be mostly focused on the laboratory activities. Each student is requested to bring to the oral exam the results of the numerical and experimental laboratories, which can be obtained either individually or in small groups of 2-3 people maximum. Upon request of the teacher, the students should be able to produce also the simulation files and the scripts developed to process the numerical and experimental data.

Bibliografia

B.R. Munson, T.H. Ohiishi, W.W. Huebsch, A.P. Rothmayer, Fundamentals of Fluid Mechanics (7th Edition), Editore: John Wiley and Sons, Anno edizione: 2013, ISBN: 9781118318676
Y.A. Cengel, J.M. Cimbala, Fluid Mechanics, Editore: McGraw-Hill, Anno edizione: 2005, ISBN: 9780071249348
H. Schlichting, K. Gersten, Boundary-layer theory, Editore: Springer, Anno edizione: 2003, ISBN: 9783540662709
S.B. Pope, Turbulent flows, Editore: Cambridge University Press, Anno edizione: 2000, ISBN: 9780521598866
H. Versteeg , W. Malalasekera, An Introduction to Computational Fluid Dynamics: The Finite Volume Method, Editore: Pearson Prentice Hall, Anno edizione: 2007, ISBN: 9780131274983

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