1. Miskam basics MISKAM – Mikroskaliges Strömung-und Ausbreitungsmodell (Microscale flow and dispersion model) Developer: Dr. J. Eichhorn, Universität Mainz (1989) Custom software : Urban ventilation & pollutant dispersion Meet VDI Richtlinie 3783 Blatt 9 german standard Validated numerical model Model setup: RANS- equation: with k- ϵ turbulence model closure Dispersion equation : passive scalar transport  One-way coupling Numerical grid  Only hexahedral, structured mesh  max. 5 millions grid cells  Rectangular block-structures buildings, vegetation, bridges/passages Boundaries Inlet: 1D logarithmic velocity profile Upper boundary: Airflow parallel to the surface Lateral boundaries: No normal velocity component Perspective view of an urban district Source: Marton Balczó 1

2. Miskam basics Pollutant emission modelling  Point source (mg/s)  Area source (mg/m 2 /s)  Line source (mg/m/s)  Differentiated by x y directions Miskam benchmark Advantages: Easy mesh generation Low CPU demand Validated for neutral atmospheric stratification Dispersion modelling of non-reactive pollutants Disadvantages: Inaccurate calculation on vertical mixing No heat transport modeling No chemical reactions No parallel simulation Terrain modelling restricted to flatland No validated model for stabil stratification No velocity profile No boundary layer resolution Modelling urban pollution dispersion by using MISKAM, 2004 Source: Márton Balczó, Gas exhaust stack of István Benkő elementary school in Újpest Urban ventillation of city centre Millenium 2

3. Guideline for numerical modeling 3

4. Start the program:  Start menu / WinMiskam.exe Step 1: Mesh generation Step 2: Fit the layout map  Load map: http://www.ara.bme.hu/oktatas/tantargy /NEPTUN/ BMEGEATMW08/2012-2013-I  Make coordinate mapping  Pixels -> layout  Coordinates -> grid Miskam tutorial 4

5. Step 3. : Digitize the buildings  Digitize/edit building  Outline the buildings by polygons  Mapping of buildings on the grid  Stop the edit process! Step 4.: Allocate the line source  Digitize/edit road net  C PM10 = 1 mg/m/s (C 24h limit = 50 μg/m 3 )  Mapping of road net on the grid  Stop the edit process! Miskam tutorial 5

6. 6 Save your mesh as campus.inp!

7. Step 5.: Wind field setup Running the flow simulation  Allocate the target directories  Run Miskam in single mode Step 6. : Concentration field setup Running the dispersion simulation Step 7. : Post-processing  Wind velocity and concentration data (read *.zwu \*.zwk files)  Horizontal and vertical slices  Pespective view of the domain ( read the *.inp file) Miskam tutorial 7

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