free surface wave

References:

1.      Chapter 3 Subrata K. Chakrabarti handbook of offshore engineering Offshore Structure Analysis vol1, Inc., Plainfield, IL, USA

2.      McCormick, M.E. (1973) Ocean Engineering Wave Mechanics. Wiley & Sons

3.      [G._B._Whitham(auth.)]_Linear_and_Nonlinear_Waves

4.      Offshore_Energy_Structure

5.      Dean, Robert George, and Robert A. Dalrymple. "Water wave mechanics for engineers and scientists." (1991).

6.       http://web.mit.edu/2.016/www/handouts/Free-Surface-Waves.pdf

7.      Currie, C. G., and Currie, I. G., Fundamental Mechanics of Fluids, 3rd Ed., Marcel Dekker, New York, 2003.

8.      Stoker, J. J., Water Waves, Interscience, New York, 1957.

9.      Henderson, F. M., Open Channel Flow, Macmillan, New York, 1966.

10.   http://folk.ntnu.no/oivarn/hercules_ntnu/LWTcourse/lwt_new_2000_Part_A.pdf

11.   J. N. Newman (1977) Marine Hydrodynamics MIT Press, Cambridge, MA.

12.   M. Faltinsen (1990), Sea Loads on Ships and Offshore Structures Cambridge University Press, Cambridge, UK.

13.   M. Rahman (1995) Water Waves: Relating modern theory to advanced engineering practice Clarendon Press, Oxford

14.   Lin, Pengzhi. Numerical modeling of water waves. CRC Press, 2008.

15.   Mader, Charles L. Numerical modeling of water waves. Crc Press, 2004.

16.      Open channel wave boundary conditions, Theory guide, fluent

17.      http://www.wikiwaves.org/Second-Order_Wave_Theory

Potential Flow

Table of Contents

• 1. potential flow vs inviscid flow
• 2. Applications
• 3. Limits
• 4. References

“When a flow is both frictionless and irrotational, pleasant things happen.” – F.M. White, Fluid Mechanics 4th ed.

potential flow

irrotational flow, a potential flow is characterized by an irrotational velocity field

in potential flow, velocity is described as gradient of velocity potential (P182 fundametal of aerodynamics, Andersion)

The irrotationality of a potential flow is due to the curl of the gradient of a scalar always being equal to zero.

Features

• potential flow describes the velocity field as the gradient of a sclar function: the velocity potential.
• viscosity = 0
• frictionless, μ = 0
• potential flow could be incompressible or compressible

Assumptions

• irrotational flow

Why is irrotational flow called potential flow? because irrotational flows can be described by the velocity potential, φ

1 potential flow vs inviscid flow

(The terms potential flow and inviscid flow are almost synonymous and are frequently used interchangeably( panton, incompressible flow)

2 Applications

• potential flow is a valid approximation for several applications,
  • flow around aircraft
    • For instance, in computational fluid dynamics, one technique is to couple a potential flow solution outside the boundary layer to a solution of the boundary layer equations inside the boundary layer.
  • groundwater flow
  • acoustics
  • water waves
  • electroosmotic flow

3 Limits

• In flow regions where vorticity is known to be important,

such as wakes and boundary layers, potential flow theory is not able to provide reasonable predictions of the flow

4 References

Chapter 6: Ideal Flow. Kundu, fluid mechanics Chapter 18: Ideal Flows in a Plane Panton, Ronald L. Incompressible Flow. 4th ed. Wiley, 2013. ISBN: 9781118013434. file:///c:/akmkemin/Backup/academic_theory_books/potential-flow file:///c:/akmkemin/Backup/academic_theory_books/potential-flow/Potential-Flow-Theory-mit.pdf

Created: 2018-08-19 Sun 18:42

Validate

convergence criterion in Fluent

There are no universal metrics for judging convergence. Residual definitions that are useful for one class of problem are sometimes misleading for other classes of problems. Therefore it is a good idea to judge convergence not only by examining residual levels, but also by monitoring relevant integrated quantities and checking for mass and energy balances.

There are three indicators that convergence has been reached:

• The residuals have decreased to a sufficient degree. The solution has converged when the Convergence Criterion for each variable has been reached. The default criterion is that each residual will be reduced to a value of less than 1e-3, except the energy residual, for which the default criterion is 1e-6. 

• The solution no longer changes with more iterations. Sometimes the residuals may not fall below the convergence criterion set in the may show that the residuals have stagnated and do not change with further iterations.This could also be considered as convergence.

• The overall mass, momentum, energy, and scalar balances are obtained. You can examine the overall mass, momentum, energy and scalar balances in the Flux Reports dialog box. The net imbalance should be less than 0.2% of the net flux through the domain when the solution has converged. In the next step you will check to see if the mass balance indicates convergence.

Reference： Fluent tutorial guide.15.0 P66

blade element momentum theory

Blade Element Momentum Theory
References:
Aerodynamics_of_Wind_Turbine,Martin Hansen,2008
Burton, Tony, et al. Wind energy handbook. John Wiley & Sons, 2001.