Table 1: Field intensity | Φ | versus the truncation number 𝑛 for different boundary conditions of the semi-infinite duct.

𝑛 𝑎 = 0 . 5 , 𝑏 = 3 𝑎 , 𝑘 = 0 . 5 , 𝑦 = 1 , 𝜉 = 1 . 5 , 𝜂 = 1 and 𝑥 = 0 . 1
| Φ | for hard boundary conditions | Φ | for soft boundary conditions

101.8091700.824323
201.8533000.878547
301.8837900.899716
401.9059800.911027
501.9227500.918070
601.9358700.922877
701.9464000.926369
801.9550500.929019
901.9622600.931100
1001.9683800.932777
1101.9736300.934157
1201.9781800.935313
1301.9821700.936295
1401.9857000.937140
1501.9888300.937874