måndag 16 juni 2014

The Ludwig Prandtl Medal

Today I received the following message:

Dear Professor Johnson, It is our great pleasure to inform you that you are the winner of the 2014 edition of the ECCOMAS Ludwig Prandtl Medal. The decision has been taken by the ECCOMAS Award Committee in a two-round voting procedure. Please receive our warmest congratulations. 

The Ludwig Prandtl Medal will be delivered at the Opening Session of the WCCM-ECCM-ECFD 2014 Conference in Barcelona, July 21, 2014 (8:30-10:30). We would very much appreciate if you can confirm your participation.

With our best regards and congratulations,

Ekkehard Ramm
ECCOMAS PresidentJosef Eberhardsteiner
ECCOMAS Secretary

Here is my answer:

Dear Profs Ramm and Eberhardsteiner

Thank you for this great honor, which I will be very happy to receive in person at the conference opening. 

The award has an interesting aspect from scientific point of view in that my work (with Johan Hoffman), shows that Prandtl's main idea of the fundamental role of the boundary layer, for both separation and drag and lift, crowning him as the Father of Moden Fluid Mechanics, is incorrect. We show that separation, drag and lift originate from instability of slightly viscous flow and not from a boundary layer. The evidence comes from solving the Navier-Stokes equations with slip boundary condition, which does not give rise to any boundary layer, and we obtain results in full agreement with observations. We conclude that separation, drag and lift in slightly viscous flow do not originate from a boundary layer and thus that Prandtl's main idea is not in agreement with observations.

I would appreciate if this will be made clear to the public at the conference and I would certainly be willing to shortly expose the reasons why Prandtl was wrong. 

The fluid dynamics community will not applaud the award, since 20th century fluid mechanics has followed the Father in search of the origin of separation, drag and lift in the boundary layer. This has had a catastrophic impact on computational fluid mechanics leading to the strong belief that correct results require resolution of boundary layers, which however is impossible even in thinkable future since quadrillions of mesh-points would be required. The result is a dead-lock of rational science. We show that drag and lift of an airplane can today be accurately computed over the entire range of angles of attack including stall, by solving the Navier-Stokes equations with slip using a couple of millions of mesh points. 

The award thus brings a major scientific question to the podium and I hope it can be accompanied by a scientific discussion.
Sincerely, Claes Johnson

5 kommentarer:

  1. Congratulations from one of your regular readers. very well deserved.

  2. Congratulations. I think you are a bit hard on Prandtl (http://en.wikipedia.org/wiki/Ludwig_Prandtl). I think he made a good contribution to engineering including chemical engineering. The fault really lies with the people who came after him. Most good professional engineers follow a code of ethics that requires them to be knowledgeable and sceptical about theory and past experiments where instruments had limited accuracy and many important factors were not measured. One part of the code of ethics (at least for engineers) is that you do not criticise other professionals unless there is a question of safety and a need to warn others. One presents results with assumptions and points out where there are differences. I am sure that plane designers have moved a long way from Prandtl's original concepts. Your work has added a new theory to the empirical work over time since Prandtl.
    Hopefully, more will see that you can make a contribution in heat transfer which climate scientists do not understand.

  3. Grattis, välförtjänt!