Vortex Theory for Bodies Moving tn Water 
DISCUSSION 
V.N. Treshchevsky 
kryloff Research Institute 
Lentngrad, U.S.S.R. 
Professor Brard has presented a very interesting paper here. 
I think it is very important and relevant, especially in cases where 
non-stationary hydrodynamic characteristics are discussed for ship 
constructions for instance, which are very difficult for calculation. 
From the other side the experimental data in this case is connected 
with insticable errors, so mutual correction with theoretical and ex- 
perimental data seems to be necessary. 
I must say that work in this direction has been carried out in 
the USSR under the connection of professors Fedayevsky and Polyakoff. 
The analysis of investigations shows that the choice of a proper scheme 
for decision ground equations, is very important because the initial 
equations for vortex density are singular. 
In this connection my first question is, what methods of prac- 
tical calculations were used and, particularly, whether the decision 
corresponds to a definite class of functions, and if so what kind of 
class is used here ? 
Another question concerns the structure of the vortex sheet 
behind and near the body. I want to ask whether in case of a wing the 
mentioned structure supposed in the sheet will correspond to Sears or 
Birnbaum representations or is it an original one ? 
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