Характеристический конус
D = {(x, t): |x − x0| < a(t0 − t)} DT = {(x, t) ∈ D: t < T} ν — единичная внешняя нормаль к DT ν = {ν1, ν2, ..., νn, νt} Ω = {x ∈ Rn: |x − x0| < at0} |
DT = S1 ∪ S2 ∪ S3
S1 = {(x, t): x ∈ , t = 0}
S2 = {(x, t): |x − x0| ≤ a(t0 − T), t = T}
S3 = {(x, t): 0 ≤ t ≤ T, |x − x0| = a(t0 − t)}