A Laboratory Study of the Effect of Surface Waves on Heat and Momentum
Transfer at High Wind Speeds
Abstract
This paper describes laboratory experiments (using a high-speed
wind-wave flume) of the effects of water waves on heat and momentum
exchange in the near-water atmospheric boundary layer at high wind
speeds. Different from previous experiments of this type, the parameters
of waves were controlled by a net stretched along the entire channel to
effectively decrease the fetch. This helped to achieve dependency of the
transfer coefficients on two independent parameters, namely the wind
speed and fetch. Another key to the experiment was using a stable
temperature stratification of the air flow, with the temperature of the
air entering the flume 15–25 degrees higher than the water. The
experiments showed a sharp increase in the heat exchange coefficient at
winds exceeding 33–35 m/s, similar to that observed earlier in the
high-speed wind-wave flume of Kyoto University with conditions of
unstable temperature stratification of the air flow. The joint analysis
of the data obtained in the high-speed wind-wave flumes of IAP RAS and
Kyoto University yields the universal dependency of the exchange
coefficients and the temperature roughness on the peak wave number of
surface wave spectra. This is independent of the type of temperature
stratification of the atmospheric boundary layer, either stable or
unstable. The sharp increase in the heat exchange coefficient is shown
to be associated with increased whitecapping.