ADREAHF
Overview presentation
Contents
 Basic information
 Intended field of application
 Model type and dimension
 Model description summary
 Model limitations/approximations
 Resolution
 Schemes
 Solution Technique
 Input
 Output quantities
 User interface availability
 User community
 Previous applications
 Documentation status
 Validation and Evaluation
 Frequently asked questions
 Prortability and computer requirements
 Availability
 Other references

Basic information (top)

Model name
ADREAHFFull model name
ADREAHFModel version and status
Version 5.0Latest date of revision
November 2009Institutions
Environmental Research Laboratory, Institute of Nuclear Technology & Radiation Protection, National Centre for Scientific Research DEMOKRITOSContact person
Dr. A.G. VenetsanosTechnical support
Provided by contact person.Level of knowledge needed to operate model
Intermediate 
Intended field of application (top)
 Prediction of flow and pollutant dispersion in complex terrain, including twophase releases.

Model type and dimension (top)
 CFD transient, threedimensional, nonhydrostatic, prognostic localscale model

Model description summary (top)
 ADREAHF is a threedimensional time dependent CFD code, to be applied for dispersion calculations in complex terrain. The working fluid is in general a multicomponent mixture, where each component can be in twophase conditions. Thermodynamic equilibrium is assumed for the mixture components. The model solves the mass, momentum and enthalpy (or internal energy) conservation equations for the mixture and the mass conservation equations for the mixture components, in Cartesian form. The liquid part of a component is obtained using Raoult’s Law. The slip velocity between liquid droplets and air is taken into account in the conservation equations. Air/ground interaction is also taken into account, by solving the transient onedimensional temperature equation inside the ground. Turbulence is modelled using models of variable complexity (zero, one, two equations). The spatial discretisation of the equations is based on the control volume approach. The computational grid is Cartesian. The momentum equations are solved on staggered grids. Complex 3d geometrical structures crossing the control volumes/surfaces of the grid are treated using the porosity approach. Time integration is based on the fully implicit scheme (1rst or 2nd order). The convective terms are discretised using the 1rst order upwind scheme or higher order schemes with flux limiters. The pressure is obtained from the continuity equation. The BICGSTAB and/or GMRES methods with various preconditioners are used for the fast and efficient solution of matrix equations.

Model limitations/approximations (top)
 Cartesian grids with porosity approach. Does not handle unstructured and/or terrain following grids.

Resolution (top)

Temporal resolution
Setup automatically by the code. The user can provide maximum convective Courant or maximum time step.Horizontal resolution
Typical horizontal cell size: 0.110mVertical resolution
Typical vertical cell size: 0.15m 
Schemes (top)

Advection & Convection
First order upwind (default).
Higher order schemes (Linear upwind, Fromm, Cubic upwind, QUICK) using flux limiters (Van Leer, Van Albada, OSPRE, MinMod, SuperB, MUSCL, Smart, Umist) formulated for nonequidistant grids.Turbulence
Standard kepsilon (default)
RNG kepsilon
Anisotropic one equation model (Bartzis)
Isotropic one equation model (Bartzis)
Generalized mixing length
LVEL modelDeposition
Deposition velocity modelChemistry
Hydrogen and methane combustion (eddy dissipation model) 
Solution technique (top)
 First or second order time integration using the fully implicit scheme.
The pressure is obtained from the fully compressible continuity equation
Matrix solvers: GaussSeidel, Line GaussSeidel, BICGSTAB and GMRES with various preconditioners (ILU(0), ILU(1), MILU(0), MILU(1))
Overall solution per time step using an iterative procedure.
Automatic step increase/decrease.

Input (top)

Emissions
For jet releases given are the jet area, velocity, temperature, pressure, pollutant mass fraction and the void fraction. Time dependent jet releases can be handled. For instantaneous releases given are the temperature, pressure, contaminant mass fraction and the void fraction at specified grid cells.Meteorology
One dimensional profile of temperature and wind data representing the undisturbed meteorological conditions are either provided or calculated by applying the model in onedimensional form in the vertical direction, with proper boundary conditions.Topography
Geometry can be constructed or imported through the code's input/output interface (EDes).Initial conditions
Initialization of a problem can be done either directly or through interpolation from a previous problem, which can have a different domain and grid.Boundary conditions
Neumann or Dirichlet or both (in case of input planes).
Transient boundary conditions available.
Constant pressure boundary planes.
Periodic boundary conditions.Data assimilation options
Not availableOther input requirements
All the input is done through the graphical user interface EDes. EDes generates all the files necessary to run the code. 
Output quantities (top)
 Optionally mixture velocity components, temperature, pressure, pollutant mass fraction, pollutant liquid fraction, turbulent viscosity, turbulent kinetic energy, dissipation rate, turbulent length scale at user specified planes.

User interface availability (top)
 GUI (in Windows) for pre and post processing, based on OpenCascade

User community (top)
 The ADREAHF code is being currently used by Universities, Research Centres, and ChemicalIndustry, in various European countries.
Users of ADREAHF should have a sufficient background on computational fluid mechanics. 
Previous applications (top)

1.Application typeUrban
UrbanApplication description
Venetsanos, A.G., Huld, T., Adams, P., Bartzis, J.G., “Source, dispersion and combustion modeling of an accidental release of hydrogen in an urban environment”, (2003) Journal of Hazardous Materials, A105, 1252.Application typeUrban
UrbanApplication description
Statharas, J.C., Venetsanos, A.G., Bartzis, J.G., W?rtz, J., Schmidtchen, U., “Analysis of data from spilling experiments performed with liquid hydrogen”, (2000) Journal of Hazardous Materials A77 (13), pp 57753.Application typeUrban
UrbanApplication description
Papanikolaou, E. A., Venetsanos, A. G., “CFD Modelling for Slow Hydrogen Releases in a Private Garage without Forced Ventilation”, International Conference on Hydrogen Safety, Pisa, Italy, 810 September, 2005 
Documentation status (top)
 Level 2 manuals

Validation and evaluation (top)
 Level 2
Simulation of the Thorney Island 8 and 21 large scale trials. Instantaneous isothermal releases of Nitrogen/Freon mixture on flat ground, without and with a semicircular fence obstacle. Simulation of the EEC55 large scale experiment. A transient release of flashing propane on flat ground, with and without a fence. Simulation of the Desert Tortoise 1 large scale experiment. A continuous release of flashing ammonia on flat ground without obstacle. Considerable liquid effects. Simulation of the FLADIST16 large scale experiment. A continuous release of flashing ammonia on flat ground without obstacle. Simulation of the EMUA1 wind tunnel experiment. A continuous release of a passive pollutant from the door of an Lshaped building. Simulation of the EMUC1 wind tunnel experiment. A continuous release of chlorine in a complex industrial site on irregular terrain, close to the sea.
ADREAHF has been included in the work of the Model Evaluation Group (MEG), Commission of the European Community, DGXII, Contact K.E.Petersen, System Analysis Department, P.O. Box 49, DK4000, Roskilde, Denmark.
ADREAHF has been validated during the EC Project SMEDIS (Scientific Model Evaluation of Dense Gas Dispersion Models) 19961999.
From 1999 and on focus has been given to the prediction of hydrogen dispersion for both cryogenic and compressed H2 releases.
ADREAHF has been significantly validated and intercompared with other CFD codes against hydrogen dispersion data within the EC projects EIHP, EIHP2, HySafe (Safety of Hydrogen as an Energy carrier, 20042009), HyPer and HyApproval.
Model intercomparison
Gallego, E., Migoya, E., MartinValdepenas, J. M., Garcia, J., Crespo, A., Venetsanos, A., Papanikolaou, E., Kumar, S., Studer, E., Hansen, O. R., Dagba, Y., Jordan, T., Jahn, W., O?ste, S., Makarov, D., An Intercomparison Exercise on the Capabilities of CFD, International Conference on Hydrogen Safety, Pisa, Italy, 810 September, 2005Input data validation
Information not available. For more details, please, refer directly to the contact person. 
Frequently asked questions (top)

 Q: What guidelines to use to construct the grid?
A: Grid refinement close to the source. For jet source cell size equal to one jet nozzle diameter For supersonic jets fictitious Birch approaches to calculate the fictitious nozzle diameter. Grid expansion far from the source. Grid expansion ratios less than 1.2 (usually 1.12) Grid as equidistant as possible. Free domain boundaries far enough from geometry to avoid effects of boundary conditions.
 Q: What guidelines to use to construct the grid?

Portability and computer requirements (top)

Portability
PCWindows version.
UNIXLINUX versions can also be provided.CPU time
A few hours  one day, depending on the simulated period and the type of machine.Storage
64128 Mbytes RAM. 200 Mbytes disk space 
Availability (top)
 The model is an inhouse/commercial CFD code. Information for obtaining ADREAHF can be provided by the contact person.

Other references (top)
 Venetsanos et al. (2009a)
 Baraldi et al. (2009)
 Venetsanos et al. (2008)
 Gallego et al (2007)
 Venetsanos and Barztis (2007)
 Venetsanos et al. (2007)
 Venetsanos et al. (2003)
 Statharas et al. (2000)

 J.G. Bartzis. Turbulent diffusion modelling for wind flow and dispersion analysis. Atmospheric Environment 23 (9), pp 19631969, 1989.
 J.G. Bartzis, ADREAHF: A threedimensional finite volume code for vapour cloud dispersion in complex terrain. Report EUR 13580 EN, 1991.
 Statharas, J.C., Bartzis, J.G., Venetsanos, A.G., W?rtz, J., Prediction of Ammonia Releases using the ADREAHF code, (1993) Process Safety Progress, 12 pp 118122.
 S. Andronopoulos, J.G. Bartzis, J. Statharas. Three dimensional modelling of dense gas dispersion. ERCOFTAC Bulletin 16, pp 1821, March 1993.
 Andronopoulos, S., Bartzis, J.G., Wurtz, J., Asimakopoulos D. Modelling the effects of obstacles on the dispersion of denserthanair gases, Journal of Hazardous Materials, 1994, 37, 327352.
 Wuertz, J.G. Bartzis, A.G. Venetsanos, S. Andronopoulos, J. Statharas, R. Nijsing. A Dense Vapour Dispersion Code Package for Applications in the Chemical and Process Industry. Journal of Hazardous Materials 46, 273284, 1996.
 J.G. Bartzis, A.G. Venetsanos, M. Varvayanni, S. Andronopoulos, S. Davakis, J. Statharas, N. Catsaros, P. Deligiannis. Wind flow and dispersion modelling over terrain of high complexity. Proceedings of the AIR POLLUTION 97 International Conference, Bologna, Italy, 1618 Sept. 97.
 Statharas, J.C., Venetsanos, A.G., Bartzis, J.G., W?rtz, J., Schmidtchen, U., “Analysis of data from spilling experiments performed with liquid hydrogen”, (2000) Journal of Hazardous Materials A77 (13), pp 5775.
 Venetsanos, A.G., Bartzis, J.G., W?rtz, J., Papailiou D.D., “Comparative modeling of a passive release from an Lshaped building using one, two and threedimensional dispersion models”, (2000) International Journal of Environment and Pollution, Vol 14, Nos. 16, pp. 324333.
 Andronopoulos, S., Grigoriadis, D., Robins, A., Venetsanos, A.G., Rafailidis, S., Bartzis, J.G., “Three dimensional modelling of concentration fluctuations in complicated geometries”, (2001) Environmental Fluid Mechanics I, pp 415440.
 Venetsanos, A.G., Vlachogiannis, D., Papadopoulos, A., Bartzis, J.G., Andronopoulos, S., “Studies on pollutant dispersion from moving vehicles”, (2002) Water, Air and Soil Pollution: Focus, Vol 2, pp 325337.
 Vlachogiannis, D., Rafailidis, S., Bartzis, J.G., Andronopoulos, S., Venetsanos, A.G., “Modelling of Flow and Pollution Dispersion in Different Urban Canyon Geometries”, (2002) Water, Air and Soil Pollution: Focus, Vol 2, pp 405417.
 Venetsanos, A.G., Huld, T., Adams, P., Bartzis, J.G., “Source, dispersion and combustion modeling of an accidental release of hydrogen in an urban environment”, (2003) Journal of Hazardous Materials, A105, 125.
 Koutsourakis, N., Neofytou, P., Venetsanos, A.G., Bartzis, J.G., “Parametric study of the dispersion aspects in a streetcanyon area”, (2005) Int. J. Environ. Pollut. 25 (14): 155163.
 Koutsourakis, N., Bartzis, J.G., Venetsanos, A.G., Rafailidis, S., “Computation of pollutant dispersion during an airplane takeoff”, (2006) Environ. Model. Softw., 21 (4): 486493.
 Neofytou, P., Venetsanos, A.G., Vlachogiannis, D., Bartzis, J.G., Scaperdas, A., “CFD simulations of the wind environment around an airport terminal building”, (2006) Environ. Model. Softw., 21 (4): 520524.
 Neofytou, P., Venetsanos, A.G., Rafailidis, S., Bartzis, J.G., “Numerical investigation of the pollution dispersion in an urban street canyon”, (2006) Environ. Model. Softw., 21 (4): 525531.