Nonlinear Evolution Equations for Broader Bandwidth Wave Packets in Crossing Sea States

Figure 1

Growth rate of instability 𝐺_𝑟=Im(Ω) against perturbation wavenumber 𝐿 for 𝜃=15°—for narrow band wave packets at fourth order: — 𝑎₁₀=𝑎₂₀=0.15, - - - - - 𝑎₁₀=0.15,  𝑎₂₀=0; at third order: - · - · - 𝑎₁₀=𝑎₂₀=0.15, ⋯𝑎₁=0.15,𝑎₂₀=0.