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Wave Forcing-欧拉嵌套理论-波浪计算

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Wave Forcing -欧拉嵌套理论

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波浪中的圆柱绕流

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Q&A                                                                                

1.    Q:计算域大小如何决定?

A:推荐浮体前后左右各1倍波长,可适当降低;或者一倍船长

2.    Q:网格如何决定?

A:保证波高方向20层以上网格,一个波长80个网格;自由液面上单个网格的长宽比1:2或者1:4,1:8;

例:波长=2m,波高0.1m;

波高方向网格=0.1m/20=0.005m,

波长方向网格=2m/80=0.025 m;

取值:波高方向=0.005m,波长方向=0.005m*4=0.02m

波长=1.5m,波高0.1m;

波高方向网格=0.1m/20=0.005m,

波长方向网格=1.5m/80=0.01875m;

取值:波高方向 = 0.01875m/4=0.0046875m,波长方向=0.01875m

3.    Q:物理模型如何选择?

A:大多数工程问题选用Realizable K-Epsilon Turbulence

4.    Q:时间步长如何确定?

A:尽量保证自由液面的Courant Number不超过0.3;

5.    Q:Wave Forcing边界类型如何定义?

A:船体四周(除对称面外)均为速度入口,设置成波浪的边界条件,激活Wave Forcing;底部设置成Wall(实际水底)或者速度入口边界,不激活Wave Forcing;

天空(Top)设置成压力出口边界,不激活Wave Forcing

6.    Q:其他注意事项?

A:二阶空间离散,二阶时间离散

7.    Q:碰到的问题?

A: 1阶波浪会出现后期波浪上漂现象; 5阶波浪正常


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