Question: Vortex Garten is a garden that alludes to the discovery of levitational force by the naturalist of what nationality?

Context paragraphs:
Botanical garden of Düsseldorf: The Botanischer Garten Düsseldorf, also known as the Botanischer Garten der Heinrich-Heine-Universität Düsseldorf and the Botanischer Garten der Universität Düsseldorf, is a botanical garden of 8 hectares maintained by the University of Düsseldorf.  It is located at Universitätsstraße 1, Düsseldorf, North Rhine-Westphalia, Germany, and open daily in the warmer months; admission is free.

Forestry Botanical Garden and Arboretum: The Forstbotanischer Garten und Pflanzengeographisches Arboretum der Universität Göttingen (Forestry Botanical Garden and Phytogeographical Arboretum of the University of Göttingen), often called the Forstbotanischer Garten und Arboretum, is a 40 ha arboretum and botanical garden maintained by the University of Göttingen.  It is located at Büsgenweg 2, Göttingen, Lower Saxony, Germany, immediately adjacent to the New Botanical Garden (Neuer Botanischer Garten der Universität Göttingen), and open to the public daily.

Loki-Schmidt-Garten: The Loki-Schmidt-Garten, also known as Botanischer Garten Hamburg, or, more formally, as Botanischer Garten der Universität Hamburg or Biozentrum Klein Flottbek und Botanischer Garten, is a botanical garden maintained by the University of Hamburg.  It has a size of around 25 hectares and is located at Ohnhorststrasse 18, Hamburg, Germany, beside the Klein Flottbek station in the Osdorf quarter, and open daily without charge.  It was renamed in 2012 after Loki Schmidt, the wife of the former German chancellor Helmut Schmidt.  Though it was renamed, the old name coexists with the new one.  Nearby Klein Flottbek station still has the second name "Botanischer Garten".

Viktor Schauberger: Viktor Schauberger (30 June 1885 in Holzschlag, Upper Austria – 25 September 1958 in Linz, Austria) was an Austrian forest caretaker, naturalist, pseudoscientistref>Ronald Engert: "Die Forellenturbine als Prinzip der kostenlosen Energiegewinnung.  Freie Energie durch Implosion". </ref>, philosopher, inventor and biomimicry experimenter.

Dresden Botanical Garden: The Botanischer Garten der Technischen Universität Dresden (3.25 hectares), also known as the Botanischer Garten Dresden or Dresden Botanical Garden, is a botanical garden maintained by the Dresden University of Technology.  It is located in the north-west section of the "Großer Garten" at Stübelallee 2, Dresden, Saxony, Germany.  It is open daily without charge.

Botanischer Garten der Universität Tübingen: The Botanischer Garten der Universität Tübingen, also known as the Botanischer Garten Tübingen or the Neuer Botanischer Garten Tübingen, is a botanical garden and arboretum maintained by the University of Tübingen.  It is located at Hartmeyerstrasse 123, Tübingen, Baden-Württemberg, Germany, and open daily.

Pinning force: Pinning force is a force acting on a pinned object from a pinning center.  In solid state physics, this most often refers to the vortex pinning, the pinning of the magnetic vortices (magnetic flux quanta, Abrikosov vortices) by different kinds of the defects in a type II superconductor.  Important quantities are the "individual" maximal pinning force, which defines the depinning of a single vortex, and an "average" pinning force, which defines the depinning of the correlated vortex structures and can be associated with the critical current density (the maximal density of non-dissipative current).  The interaction of the correlated vortex lattice with system of pinning centers forms the magnetic phase diagram of the vortex matter in superconductors.  This phase diagram is especially rich for high temperature superconductors (HTSC) where the thermo-activation processes are essential.

Vortex Garten: The Vortex Garden is a privately owned public garden in the Hessian city of Darmstadt (Germany).  It is a pantheistic permaculture garden at the art nouveau area of Mathildenhoehe and alludes to Viktor Schauberger’s discovery of “levitational force” through artistic depictions by internationally renowned sculptors including John Wilkes, Jacopo Foggini, Jerome Abel Seguin and Hyesung Hyun.  The garden is the private property of Henry Nold of Darmstadt, but is open to the public.

Botanischer Garten Duisburg-Hamborn: The Botanischer Garten Duisburg-Hamborn, also known as the Botanischer Garten Duisburg or the Botanischer Garten Hamborn, is a municipal botanical garden and aquarium located at Fürst-Pückler-Straße 18, Duisburg, North Rhine-Westphalia, Germany.  It is open daily, and should not be confused with the Botanischer Garten Kaiserberg, another botanical garden in Duisburg.

Botanischer Garten Aachen: The Botanischer Garten Aachen (1.2 hectares) is a botanical garden maintained by RWTH Aachen.  It is variously known as the Botanische Garten der RWTH Aachen, more formally the Botanische Garten der Rheinisch-Westfälische Technische Hochschule Aachen, and sometimes the Freundeskreis Botanischer Garten or Biologischen Zentrums Aachen BIOZAC für Ökologie und Umweltpädagogik.  It is located at Melatener Straße 30, Aachen, North Rhine-Westphalia, Germany, with a new addition (the Karl Garten) located on Rabentalweg.  Both are open daily without charge.

Supporting paragraphs: Vortex Garten Viktor Schauberger
Answer: Austrian