I cannot really understand the question. please see the following paper. It might give an initial insight about head loss in hydraulic structures head loss...for supplemental information, please keep me updated.

Modeling energy dissipation over stepped spillways using machine learning approaches

K Roushangar, S Akhgar, F Salmasi, J Shiri - Journal of Hydrology, 2014 - Elsevier

Under turbulent flows through pipes, a number of experiments were conducted and is being undertaken with various fluids. The existing equations predict the losses satisfactorily. However, with improvement in manufacturing processes, the surface roughness will reduce with surface coatings with nanoparticles. This will enable transport of liquids with lower pressure drop. I think this is a good area for further study and research.

Energy dissipation in hydraulics is in fact a very large and decisive field. Local energy losses are a very relevant matter in some hydraulic structures, particularly in open channel flows (as in the example presented by Jalal Shiri), and a gap in the technical literature and research seem still often to occur (these energy losses are called and treated frequently as “minor losses”, perhaps wrongly). My question is basically directed to the continuous head losses (as excellently understood by K V Sharma). I thank both fruitful contributions. In hydraulic engineering applications, it is frequently still used the Manning Equation (or the Chézy equation) in open channel flow, and the Colebrook-white equation (or its approximations) and the Hazen Williams equation in pipe flow. Similarly empirical correlations are used in multiphase water flows (I can refer for instance the Lockhart and Martinelli method and its developments). Several possible turbulence models and its simplifications are also a related field of research. So the question is: Is this procedure satisfactory? What are the best current approaches and what should be direction of the research in this fundamental area?

Antônio.

.

Although the first edition has over 50 years work IDELCHICIK Handbook of Hydraulic Resistance shows up still insuperable. Since the first edition in French in 1969 (Memento des pertes  charge, Eyolles, Paris before the Russian had I not had access) to the last in 2003 (Handbook of Hydraulic Resistance, Jaico Publishing House, Ahmedabad) were incorporated more coefficients and some more items.

.

But unfortunately nowadays we have more people with erudition and patience to edit basic books like this.

.

In the two-phase flow there is virtually nothing in this text, and the time of authors who took years to build large texts like this and Schlichting in Boundary Layer Theory, has passed. Unfortunately someone take five years to make a compilation of important parts of science will be considered unproductive and before you finish your work you might lose your rank or its financing.

.

I'm giving this not very objective answer because I see that we may have to reverse this process, under penalty of young researchers for lack of books began to weight "reinventing the wheel" because the culture of reading only articles of the past five years!

.

References localized losses for two-phase flow there is only so scattered in articles by Congress do not reach the "level" of novelty required by leading journals.

.

The current books that seek to present news in a broader way are true "patchworks" in which several experts write parts and the figures of the true editor, which should match not only the notation, but how to eliminate overlap and fill gaps disappeared. I've given up buying books that feature the author as "edited by" for the latest experiences are real disasters.

.

Always told my students that an opera can not be composed only of "prima donnas", but nowadays nobody wants to belong to the "choir", knowing that for an opera works to "prima donna" should only be one!

.

All I can say is. Remember. Experimental essays in basic know geometries are not yet equalled nor surpassed by CFD. The drawback is in the lack of generality. So. If you geometry and conditions are those of the references, or they are sufficiently close to these, You can rely on the results peacefully. The procedure is absolutely satisfactory. Indeed, are these old experiments the yardstick for calibrating modern computational tools.

The field of two-phase flow is now very active. At les in respect to computational modeling. On the "empirical approach" side (gas-liquid) You might find a lot of material in books and journals over heat and mass transfer.

"the culture of reading only articles of the past five years!".... "I've given up buying books that feature the author as "edited by" for the latest experiences are real disasters.". I agree Mr Maestri!. A valuable commentary. Too hurried, to (s)new, and nobody appreciate the excellent work of the old thinkers.

I often remark that none good book of water turbines  (comprehensive and detailed) has been written since  late 50's. Incredible!

I agree that the experience and the irreverence are essential. In a civil engineering context, the construction of houses does not begin by the roof, as the “prima donna” more than all the “choir” needs first to clearly understand the music. In aeronautics, humans did not stop with the first balloon that was built, and the irreverence from the renascence was perhaps a fundamental step for the current planes and spatial search. I learned that the human species only use typically a very little part of its neuronal capacity.

With respect to the question that I made, perhaps the answer is not very easy. For hydraulic modeling of sewers in urban drainage systems, for example, this paper in Portuguese available in this portal (that I wrote several years ago) did use several (empirical) flow resistance laws that were assumed suitable for steady uniform flow and gradually varied unsteady flow: “Modelação Hidráulica em Colectores de Sistemas Urbanos de Drenagem”

A comprehensive  discussion of this issue you can find in:

H. Herwig, B. Schmandt: How to Determine Losses in a Flow Field: A Paradigm Shift Towards the Second Law Analysis, Entropy, Vol.16, 2959- 2989 , 2014

which you can download from my research gate page.

regards

H.Herwig

The discussion, based on a thermodynamic approach, is absolutely pertinent. I fully agree when Heinz Herwig and Bastian Schmandt wrote that ”it is attractive to relate the losses in a flow field immediately to the cause of it and not to certain consequences of it.”. Certainly the difficulty is to find a simple, comprehensive and accurate turbulent model for describing the flow fields.

The turbulent characteristics of flow are explained by Ludwig Prandtl and later by a number of investigators.  It started with the two layer theory of turbulence and subsequently improved to a three layer model with the inclusion of a buffer region. These are developed as discrete regions in the flow field.  Later, efforts were made to reflect the turbulent characteristics with a single equation  (eddy diffusivity equation) by van Driest, Kato and others.  A relatively good understanding of the turbulent model can be read from the book by Cebeci.  

It is an excellent starting point. For example, this Internet pdf file mention the existence of about 200 eddy viscosity models (including the brilliant Prandtl Mixing Length): “Simulation of Turbulent Flows - Stanford University”.

https://www.nuclear-power.com/nuclear-engineering/fluid-dynamics/bernoullis-equation-bernoullis-principle/head-loss/

There are several approaches for computing head losses that occur in turbulent flows of water. One common approach is to use empirical equations that relate head loss to flow rate, pipe diameter, and other parameters.