Backward differentiation formula finite difference schemes for diffusion equations with an obstacle term

Olivier Bokanowski (1) , Kristian Debrabant

1 LJLL - Laboratoire Jacques-Louis Lions

Finite difference schemes, using Backward Differentiation Formula (BDF), are studied for the approximation of one-dimensional diffusion equations with an obstacle term, of the form $$\min(v_t - a(t,x) v_{xx} + b(t,x) v_x + r(t,x) v, v- \varphi(t,x))= f(t,x).$$ {For the scheme building on the second order BDF formula (BDF2), we discuss unconditional stability, prove an $L^2$-error estimate and show numerically second order convergence, in both space and time, unconditionally on the ratio of the mesh steps. In the analysis, an equivalence of the obstacle equation with a Hamilton-Jacobi-Bellman equation is mentioned, and a Crank-Nicolson scheme is tested in this context. Two academic problems for parabolic equations with an obstacle term with explicit solutions and the American option problem in mathematical finance are used for numerical tests.

Mots clés: finite difference scheme; numerical methods; diffusion equation; obstacle equation; viscosity solution; Crank Nicolson scheme; Backward Differentiation Formula; high order schemes

Domaines: Analyse numérique [math.NA]

Olivier Bokanowski, Kristian Debrabant. Backward differentiation formula finite difference schemes for diffusion equations with an obstacle term. IMA Journal of Numerical Analysis, In press, ⟨10.1093/imanum/draa014⟩. ⟨hal-01686742v2⟩