Zhuo Heng




Zhou Heng, working in the field of mechanics, was born in Shanghai on 20 November 1929. He graduated from the Department of Hydraulic Engineering of Peiyang University in 1950. Since then, he works in Peiyang and Tianjin University. He has been the head of the Department of Mechanics and the Dean of Graduate School of Tianjin University.
In 1956, he solved a problem in the theory of optimal control.
In nineteen sixties, he proved the expansion theorems for the eigenvalue problem of Orr-Sommerfeld equation which is non-selfadjoint, and extended the Liapounoff's theorem in the theory of stability of motion to the case for continuum mechanics. Then he was able to prove the theorem of conditional stability of fluid motion. 
From 1972 to 1976, he worked together with people in a factory to design gyroscopes with two degree of freedom and with gas dynamic bearings, for which he solved the problem of vibration of the gyroscope due to the interaction of the rotor and bearings.
Starting from 1979, his main interests are theory of hydrodynamic stability and turbulence. In 1981, he proposed a new method in the weakly nonlinear theory of hydrodynamic stability. Later, he found that the then prevailing weakly nonlinear theory of hydrodynamic stability suffered from some fundamental weaknesses. He successfully improved the theory, such that the improved theory can offer, under a certain condition, convergent solution, while the original theory always provides divergent solution. Also, the improved theory can offer solutions correspond to both transient state and steady state, while the original theory is only suitable for steady state.
He applied the idea of hydrodynamic stability to problems of coherent structures in turbulent flows, proposed dynamic models for the coherent structure, thus was able to explain some important feature of coherent structures observed in experiments, which was not able to explain previously. The proposed model was then applied to the problem of heat transfer of a turbulent boundary layer, which is an important technical problem.
Due to his contribution in the theory of hydrodynamic stability, he has been awarded with a second rank National Award of Natural Sciences in 1987. He was elected to be a member of Chinese Academy of Sciences in 1993.