Skip to main content

RESEARCH ON CONTINUOUS AND INSTANTANEOUS HEAVY GAS CLOUDS

Objective

TO PROVIDE IMPROVED METHODS WHETHER NUMERICAL OR PHYSICAL TO PREDICT THE BEHAVIOUR OF HEAVY GAS CLOUDS.
Despite big advances in numerical modelling, there are a number of problems in meteorology for which mathematical solutions can either not be found or can only be found at a disproportionately high expense. This is especially so with the modelling of pollutant dispersal under the influence of obstructions (buildings, etc) in urban surroundings. As an alternative, there is the analogous simulation of such processes on a reduced scale in a wind tunnel. At the Meteorological Institute, such techniques of simulation are developed and applied.

Expertise is available in the following:
physical modelling of the dispersion of waste heat and exhaust gas;
dispersion of heavy gases;
examination of the influence of building and hills on the dispersion of exhaust gas;
effects of wind on buildings;
measures to reduce wind effects.
THE PROGRAM OF HAMBURG UNIVERSITY AIMS AT QUANTIFYING THE EFFECTS OF DIFFERENT SOURCE TYPES AND OF OBSTRUCTIONS ON HEAVY GAS DISPERSION. A LARGE NUMBER OF TERRAIN FEATURES AND MAN-MADE OBSTACLES (DAMS, SLOPES, STREET CANYONS, INDUSTRIAL AND URBAN STRUCTURES) WILL BE INVESTIGATED. THE RESULTS WILL BE DIRECTLY APPLICABLE FOR IMPROVED RISK ASSESSMENT ANALYSES. FURTHERMORE, A DATA BASE WILL BE CREATED FOR NUMERICAL MODEL VERIFICATION PURPOSES.
THE WORK AT HAMBURG WILL CONCENTRATE ON EXPLORING WORST CASE CONDITIONS FOR RISKS OF PRACTICAL INTEREST, I.E. FOR A GIVEN VOLUME OF A HEAVY GAS WITH KNOWN PROPERTIES IN A GIVEN ENVIRONMENT, THE WORST RELEASE CONDITIONS IN COMBINATION WITH THE WORST WIND SPEED AND WIND DIRECTION WILL BE FOUND OUT. IN CASE OF A FLAMMABLE GAS, FOR INSTANCE, THE LONGEST POSSIBLE LOWER FLAMMABILITY DISTANCE WOULD THEREBY BE DETERMINED. IN MANY PRACTICAL APPLICATIONS, THE KNOWLEDGE OF SUCH A DISTANCE WOULD GREATLY SIMPLIFY THE LICENSING PROCEDURE SINCE THE AUTHORITIES HAD TO REQUIRE INDIVIDUAL CASE STUDIES ONLY FOR CASES IN WHICH THE POSSIBLE LENGTH OF THE HAZARDOUS ZONE IS INACCEPTABLY LARGE.
FIRST RESULTS OBTAINED IN A COMPLEMENTARY NATIONAL RESEARCH PROJECT INDICATE, THAT WORST CASE SITUATIONS ARE COMMONLY CONNECTED TO INSTANTANEOUS RELEASES. THEREFORE THE WORK DONE IN HAMBURG WILL CONCENTRATE MAINLY ON THIS TYPE TO RELEASE. THE RESEARCH WORK IN HAMBURG WILL COVER ABOUT 20 TO 30 SOURCE/SURROUNDING-COMBINATIONS OF PRACTICAL INTEREST. TAKING INTO CONSIDERATION THAT, DUE TO THE NATURAL VARIABILITY OF TURBULENT DISPERSION PROCESSES, EACH INDIVIDUAL CASE HAS TO BE REPEATED UP TO TEN TIMES OR MORE, SEVERAL HUNDRED SINGLE EXPERIMENTS WILL BE CARRIED OUT. THE EXPERIMENTAL PROGRAM INCLUDES BOTH, MEAN AND CONCENTRATION FLUCTUATION MEASUREMENTS.
THE SPECIFIC OBSTRUCTIONS TO BE INVESTIGATED WILL BE DETERMINED AFTER COMPLETION OF PHASE 0 IN ACCORDANCE WITH OUR PARTNERS IN THE JOINT PROJECT. THE PROGRAM SHOULD, HOWEVER, INCLUDE A VARIETY OF TERRAIN FEATURES LIKE DAMS, SLOPES, DITCHES OR RIVER BEDS ETC.
THE RESULTS OBTAINED WILL BE GENERALIZED THROUGH DIMENSIONAL ANALYSIS. TOGETHER WITH THE RESULTS OBTAINED IN THE EXPERIMENTS OF PARTNERS PROJECT AT TNO, A DATA BASE COVERING THE EFFECTS OF AT LEAST THE MOST IMPORTANT SOURCE/OBSTACLE COMBINATIONS ON HEAVY GAS DISPERSION WILL BE CREATED.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

UNIVERSITY OF HAMBURG
Address
Bundesstrasse 55
20146 Hamburg
Germany