Prof. Dr. Florian Frank

Veröffentlichungen

Projekte

• Der Einfluss von Kolloiden auf Wasserfluss und Stofftransport in Böden: Randaspekt oder Schlüsselprozess?
  (Drittmittelfinanzierte Einzelförderung)
  Laufzeit: 01-11-2006 - 31-12-2009
  Mittelgeber: DFG-Einzelförderung / Sachbeihilfe (EIN-SBH)
  Abstract

  Soil colloids may influence the interaction between solutes and the
  immobile solid phase. A coupling to the fluid transport is possible by
  processes of sedimentation, flocculation, precipitation, filtration and
  deposition. The objective of this research project is the qualitative
  and quantitative examination of the crucial aspects of
  colloidal-influenced solute- and fluid transport by means of systematic,
  prognostic simulation. In detail,

  1. the attachment and detachment of colloids under consideration air-water interface of the soil,
  2. the transformation of the pore space and the thus induced coupling to the fluid transport in soil, and
  3. the transformation of the surface properties of the solid phase and the thus induced coupling to the solute transport

  have to be analyzed. The main hypothesis of this project states that
  the couplings incorporated in the model conception affect the
  praxis-relevant situations not only qualitatively, but also
  quantitatively in a significant way. The deterministic description of
  the physicochemical mechanisms on basis of the conservation laws for
  mass, impulse and energy results in systems of time-dependent non-linear
  partial differential equations. In order to make the model operative
  with respect to the problem formulation, one has to approximate it via
  numerical methods and to implement those in a software tool. For each
  level of complexity which has to be achieved, a comparison with existing
  experimental data has to be accomplished. In particular, these datasets
  have is to be used to obtain a realistic parametrization of the model
  via inverse modelling.

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• Modellierung des reaktiven Transports von Schadstoffen in der (un-)gesättigten Bodenzone zur Prognose der natürlichen Selbstreinigung
  (Drittmittelfinanzierte Gruppenförderung – Teilprojekt)
  Titel des Gesamtprojektes: Kontrollierter natürlicher Rückhalt und Abbau von Schadstoffen bei der Sanierung kontaminierter Böden und Grundwässer (BMBF Förderschwerpunkt KORA)
  Laufzeit: 01-04-2004 - 31-12-2008
  Mittelgeber: BMBF / Verbundprojekt
  Abstract

  The evaluation of the potential of contaminated sites concerning natural
  attenuation needs comprehensive process descriptions and accurate,
  reliable numerical algorithms. Numerical errors may lead to
  qualitatively completely wrong conclusions concerning the potential of
  the site for degradation. It has been developed a comprehensive and
  flexible simulation tool, that is outstanding concerning the variety of
  processes, the quality and efficiency of the calculations ensured by
  modern numerical methods as well as the usability. The existing software
  platform RICHY has been extended, which is already intensely and
  successfully used by universities, institutes and consultants for the
  simulation of reactive transport and parameter identification. Among
  previous modules for coupled sufactant transport, preferential,
  unsaturated flow or carrier facilitated transport the project could
  realize new model components that surpass most of all existing software
  packages. The extensions contain complete descriptions of microbially
  catalysed degradation with arbitrary reaction partners and inhibition,
  general multicomponent reactions including the effects of ionic
  strength, as well as mineral dissolution and precipitation. The
  efficient and highly accurate, newly developed mathematical solution
  algorithms for the resulting coupled systems of partial differential
  equations could show their quality in complex international benchmark
  studies. Locally mass conserving, mixed hybrid finite element
  discretisations of the flow problem have been combined with globally
  implicit, reactive multicomponent models. Novel reduction methods for
  the latter rely on the linear transformation of the equation systems and
  variables and lead to the consideration of conservation quantities
  which can be handled efficiently, as a part of the transport – reaction
  – equations decouples. Another approach that has been pursued
  simultaneously relies on a modified Newton method and results in
  efficiency enhancements by the neglection of coupling terms in the
  Jacobian matrix. This algorithm can be applied fully adaptively, in 1D
  as well as in 2D. Both approaches could be combined with adaptive
  techniques for the automatic, efficient choice of time steps and spatial
  grid sizes, which makes the calculation of these complex problems
  feasible on PCs.
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