Introduction of dissipation in potential flows
Introduction of dissipation in potential flows
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发表时间：
2011
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通讯作者：
X. B. Chen;F. Dias;W. Duan
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作者：
X. B. Chen;F. Dias;W. Duan
通过对线性不可压NS方程的联合Fourier-Laplace变换分析，在线性势流框架下，结合自由表面的运动学和动力学条件、粘性项和表面张力，建立了新的计算公式。考虑到大的耗散发生在身体船体附近，那里有大的运动学的流动分离，我们采用的概念，相当完美的流体引入耗散力的大小成比例的流体速度，但在相反的方向。这个概念被扩展到定义在身体船体附近的一些耗散表面上的压力损失。应用绿色定理，得到了包含耗散面的新积分方程。结果表明，消能效果是相当有效的，相关系数可以通过模型试验或/和CFD计算来确定。
New formulations combining the kinematic and dynamic conditions over the free surface with viscous terms and surface tension have been developed within the linear potential flow framework, through the analysis on the linear incompressible NS equations by the joint Fourier-Laplace transform. Considering the fact that large dissipation occurs in the vicinity of body hull where there is flow separation of large kinematics, we adopt the notion of fairly perfect fluid introducing a dissipation force proportional to the magnitude of fluid velocity but in the opposite direction. This notion is extended to define a pressure loss across some dissipative surfaces in the vicinity of body hull. The new integral equation is then obtained to include the dissipative surface, by applying the Green theorem. It is shown that the dissipation effect is quite effective and the associated coefficient can be determined by model tests or/and CFD computations.