estratto_physical_hydraulic

Physical Hydraulic models past and present Attilio Adami aadami@protecno.it

Š 2013, Marcianum Press, Venezia Dorsoduro 1 - 30123 Venezia

Progetto e grafica di copertina: design Tomomot Celso Costantini, Arcivescovo titolare di Teodosia, Delegato Apostolico in Cina.

1933, medaglia, bronzo, Ă˜11,1. Autore: Pietro Giampaoli (1898-1998).

Impaginazione e grafica: Linotipia Antoniana - Padova

ISBN 978-88-6512-171-9

INDEX

List of contributors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

7 9

First part: TheoreTical approach To The similariTy 1. Dimensional analysis and non dimensional groups in hydraulics . . .

1.1. Physical quantities: a statement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1.2. The concept of dimension . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1.3. Systems of measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1.4. The independent quantities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1.5. The laws of physics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1.6. The theorem Î . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1.7. Dimensional analysis and fluid mechanics . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1.8. Validity of Dimensional Analysis in Fluid Mechanics . . . . . . . . . . . . . . . . .

15 15 17 21 22 23 26 27 31

2. Theory of similarity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2.1. Definition of the problem and general theorem . . . . . . . . . . . . . . . . . . . . . .

2.2. Conditions of similarity from Dimensional Analysis . . . . . . . . . . . . . . . . . .

2.3. Conditions of similarity from Inspectional Analysis . . . . . . . . . . . . . . . . . .

2.4. Validity of the Theory of Similarity in Fluid Mechanics . . . . . . . . . . . . . . .

35 35 36 37 38

3. The theory of models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3.1. Introductory note . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3.2. The geometric similarity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3.3. The cinematic similarity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3.4. The dynamic similarity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3.5. Similarity of Euler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3.6. Similarity in cavitation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3.7. Similarity of Reynolds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3.8. Similarity of Mach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3.9. Similarity in water hammer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3.10. The Froude similarity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3.11. Tilted models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3.12. Distorted models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3.13. Similarity in waves phenomena (Alvise Benetazzo, Eleonora Dallan) 3.13.1. Water wave mechanics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

41 41 42 43 43 44 45 46 47 47 49 51 52 56 56

4

3.13.2. Modeling laws . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3.13.3. Froude similitude; Reynolds similitude . . . . . . . . . . . . . . . . . . . . . . . .

3.13.4. Chauchy similitude . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3.13.5. Testing facilities and instrumentations . . . . . . . . . . . . . . . . . . . . . . .

3.14. Similarity in solid transport phenomena (Enrico Serafini) . . . . . . . . . .

3.14.1. Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3.14.2. Generalities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3.14.3. Conditions for the hydrodynamic similarity . . . . . . . . . . . . . . . . . .

3.14.4. Conditions for the solid transport similarity . . . . . . . . . . . . . . . . . .

3.14.5. The similarity in the phenomena with prevalent bed load transport . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3.14.6. The similarity in the phenomena with dominant sediment transport in suspension . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3.14.7. Closing remarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3.15. Similarity in fluid-structure interaction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

58 60 62 63 67 67 68 69 70 71 74 77 80

second part: applieD cases 4. most interesting applied cases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.1. Pressure flows (Corrado Avanzi) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.1.1. Steady conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.1.2. Unsteady conditions (surge tanks) . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.2. Dams outlets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.2.1. Spillways . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.2.2. Energy dissipators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.2.3. Deep outlets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.3. Navigation locks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.4. River models (Matteo Volpato) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.4.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.4.2. Similarity Mechanics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.4.3. River models classification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.4.4. River models with fixed bed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.4.5. River models with mobile bed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.4.6. Case study . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.5. Local scour due to presence of structures (Enrico Serafini) . . . . . . . . .

4.5.1. Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.5.2. Local erosion – State of knowledge . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.5.3. The role of physical modelling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.5.4. The physical model of the pile of the new rail bridge on Po river at Piacenza . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.5.5. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

85 85 85 86 91 92 93 93 94 95 95 98 100 103 113 117 127 127 127 132 136 144

5

4.6. Fluvial mobile bed models with light material (Aronne Armanini, Maurizio Righetti) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.6.1. Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.6.2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.6.3. Scale criteria in the fluvial models . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.6.4. Application to a fluvial groynes system . . . . . . . . . . . . . . . . . . . . . . .

4.6.5. Characteristics of the scale reduced model . . . . . . . . . . . . . . . . . . .

4.6.6. Analysis of the results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.6.7. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.7. Hydraulic models for the effect of landslides in lakes and reservoirs (Marcello Benedini) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.7.1. A frequent risk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.7.2. Types of landslides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.7.3. Tools for analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.7.4. Similitude criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.7.5. Two-dimension analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.7.6. The control of landslide velocity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.7.7. Three-dimension models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.7.8. The flow over the dam . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.7.9. Calibration and validation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.8. Bays and lagoons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.9. Maritime works (Alberto Venuti, Francesco Barbariol) . . . . . . . . . . . . . . .

4.9.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.9.2. Similitude criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.9.3. Similitude criteria for Rubble Mound Breakwaters . . . . . . . . . . .

4.9.4. Vertical wall breakwaters small scale models . . . . . . . . . . . . . . . .

4.9.5. Scale effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.9.6. Stability tests of Venice lagoon inlets external breakwaters . .

4.9.7. Model tests for Gioia Tauro harbour caissons dam . . . . . . . . . . .

4.10. Modeling of environment (Alvise Benetazzo e Eleonora Dallan) . . . . .

4.10.1. Waves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.10.2. Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.10.3. Wind . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.10.4. Combined wave, current and wind generation . . . . . . . . . . . . . . . .

4.10.5. Modeling of offshore structures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.11. Littoral Reclamation (Alberto Venuti, Mirco Vandelli) . . . . . . . . . . . . . . . .

4.11.1. The physical models in coastal process . . . . . . . . . . . . . . . . . . . . . . .

4.11.2. Review of coastal phenomena . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.11.3. Scaling laws . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.11.4. Similitude criteria for cross shore profile modelling . . . . . . . . . .

4.11.5. Similitude criteria for wave induced bed load transport . . . . . .

4.11.6. Fixed bed tracer models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.11.7. Lightweight material models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.11.8. Model’s testing procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

149 149 149 150 156 157 159 162 164 164 165 166 167 168 169 172 175 175 179 182 182 185 186 190 193 205 214 218 218 220 221 222 223 231 231 234 237 240 246 248 249 249

6

4.11.9. Physical model of the mouth of the river Sile . . . . . . . . . . . . . . . . .

4.12. Waves-structures interactions (Elena Adami, Alberto Venuti) . . . . . . . .

4.12.1. The behavior of the MOSE’s gates: studies on models . . . . . . . . .

250 267 267

5. analogic models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5.1. Hele Shaw Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5.2. Hydrodynamic models of sails (Giampaolo Di Silvio) . . . . . . . . . . . . . . . .

5.2.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5.2.2. Experimental set-up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5.2.3. Similitude requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5.2.4. Propagation of perturbations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5.2.5. Combining the similitude criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5.2.6. Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5.2.7. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5.3. Aerodynamics models in hydraulic (Fabio Nadalini) . . . . . . . . . . . . . . . . .

5.3.1. Theoretical approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5.3.2. A practical application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

285 285 287 287 287 289 290 291 292 300 302 302 310

6. model construction technique (Giannarturo Còmola) . . . . . . . . . . . . . . . . .

6.1. Containment Construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.1.1. Fluvial models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.1.2. Maritime Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.2. Hydraulic facilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.2.1. Recirculating pump systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.2.2. Gravity Feed Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.3. Wave generators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.4. Methods of construction and assembly works . . . . . . . . . . . . . . . . . . . . . . .

6.4.1. Implementation of models of marine works . . . . . . . . . . . . . . . . . . .

6.4.2. River works models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.4.3. Implementation of models of pipelines, tunnels and outlet works . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.4.4. Construction of models of dams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

319 319 319 319 322 322 324 324 325 325 329 335 337

copyright notice Figures of the notes “Pressure flows” by Corrado Avanzi and “Hydrodynamics models of sails” by Giampaolo Di Silvio come from the archives of the Institute of Hydraulics, University of Padua, now the Department of Civil and Environmental Engineering.

Figures of the note “Fluvial movable bed models with light material” by Aronen Armanini and Maurizio Righetti come from the archives of Cudam (University Centre for the Defence of the Mountain Environment” of the University of Trento.

Figures of the note “Hydraulic models for the effect of landslides in lakes and reservoirs” by Marcello Benedini are property of the author.

All other figures in this volume are drawn from studies conducted by the Italian Ministry of Infrastructure and Transport – Venice Water Authority, trough its concessionaire Consorzio Venezia Nuova.

7

LIST OF CONTRIBUTORS Attilio Adami:

Protecno S.r.l., Padova. aadami@protecno.it

Elena Adami:

Protecno S.r.l., Padova. eleadami@protecno.it

Aronne Armanini:

Università di Trento. aronne.armanini@unitn.it

Corrado Avanzi:

Università di Padova. Corrado.avanzi@unipd.it

Francesco Barbariol:

Università di Padova. francesco.barbariol@unipd.it

Alvise Benetazzo:

ISMAR-CNR, Venezia. alvise.benetazzo@ve.ismar.cnr.it

Giannarturo Còmola:

Protecno S.r.l., Padova. gcomola@protecno.it

Eleonora Dallan:

Protecno S.r.l., Padova. edallan@protecno.it

Giampaolo Di Silvio:

Università di Padova. giampaolo.disilvio@unipd.it

Fabio Nadalini:

fnada@vodafone.it

Maurizio Righetti:

Università di Trento. maurizio.righetti@unitn.it

Enrico Serafini:

Protecno S.r.l., Padova. eserafini@protecno.it

Matteo Volpato:

Protecno S.r.l., Padova. mvolpato@protecno.it

Mirco Vandelli:

Protecno S.r.l., Padova. mvandelli@protecno.it

Alberto Venuti:

Protecno S.r.l., Padova. avenuti@protecno.it

9

FOREWORD

It’s a well-known fact that fluid mechanics and hydraulics with it are the branches of physics where the experimental approach in the research had the greatest development. Although the reasons are known: in the equations of fluid mechanics non linear terms often appear that can not be neglected, the differential equations are complex and can be integrated only in some simple cases, the contours of the phenomena under study are very articulated and complex, making even more difficult to solve them analytically. The proof of these difficulties can be found in the old texts on hydraulics, in the first half of the twentieth century, which were the only textbooks for engineers who showed numerical or graphical methods to solve many problems: the fluctuations in the surge tanks, water hammer pressures, the free level profiles of gradually varied flow in channels are only perhaps the most famous cases, even then solved with numerical methods. The interest in the experimental approach in the research derives exactly from the said difficulties of the analytical method and this also explains the great development of hydraulic research laboratories, which reached in some cases large dimensions.

During the same period of the last century were developed in the Dimensional Analysis and the Theory of Similarity, which allowed the correct setting and developing of the various particular researches.

And when it was necessary to examine the behaviour of a great and expensive work with important interferences with the territory, it was logic to build an experimental equipment dedicated to that work, which ultimately was indicated as the “hydraulic model” of that work. The word “model” is borrowed from architecture and is as old as it is directly derived from the Latin word “modellus” which is short for “modus” meaning “measure”. In the old days, when an architect wanted to illustrate his new idea was building a good reproduction in three dimensions on a smaller scale of the of the new work. On the other hand, the hydraulic model, as discussed below, must respect the geometric similarity and the final result is very similar to an architectural model.

For several decades, the hydraulic model was the most powerful means of control of major projects, also enjoying a high esteem by the most experienced researchers in hydraulic, so that the legislation of many countries foresaw mandatory controlling major projects with the physical model. And no doubt that the research that accompanied the hydraulic model was very significant: as proven by the scientific production on this topic, important and large, at least for the time.

The unchallenged power of the physical model did not have a long duration, let say fifty-sixty years, since starting in about 1960 the successful life of computing machines began and they gave great impetus to numerical methods for solving complex calculations. It was natural to think of a specific numerical program for predicting the behaviour of a single work, which was called by analogy “mathemat-