|
| 1 | +# Flow in a Channel Problem |
| 2 | +# Collocation formulation |
| 3 | +# Alexander S. Bondarenko - Summer 1998 |
| 4 | +# COPS 2.0 - September 2000 |
| 5 | +# COPS 3.0 - November 2002 |
| 6 | +# COPS 3.1 - March 2004 |
| 7 | + |
| 8 | +function channel_model(nh; T = Float64, backend = nothing, kwargs...) |
| 9 | + nc = 4 |
| 10 | + nd = 4 |
| 11 | + R = 10.0 # Reynolds number |
| 12 | + tf = 1.0 |
| 13 | + h = tf / nh |
| 14 | + |
| 15 | + bc = [0.0 1.0; 0.0 0.0] |
| 16 | + rho = [0.06943184420297, 0.33000947820757, 0.66999052179243, 0.93056815579703] |
| 17 | + t = [(i-1)*h for i in 1:nh+1] |
| 18 | + |
| 19 | + # Initial value |
| 20 | + v0 = zeros(nh, nd) |
| 21 | + for i in 1:nh |
| 22 | + v0[i, 1] = t[i]^2*(3.0 - 2.0*t[i]) |
| 23 | + v0[i, 2] = 6*t[i]*(1.0 - t[i]) |
| 24 | + v0[i, 3] = 6*(1.0 - 2.0*t[i]) |
| 25 | + v0[i, 4] = -12.0 |
| 26 | + end |
| 27 | + |
| 28 | + core = ExaModels.ExaCore(T; backend= backend) |
| 29 | + |
| 30 | + v = ExaModels.variable(model, 1:nh, 1:nd) |
| 31 | + w = ExaModels.variable(model, 1:nh, 1:nc; start=0.0) |
| 32 | + |
| 33 | + uc = ExaModels.variable(model, 1:nh, 1:nc, 1:nd; start=[v0[i, s] for i=1:nh, j=1:nc, s=1:nd]) |
| 34 | + Duv = ExaModels.variable(model, 1:nh, 1:nc, 1:nd; start=0.0) |
| 35 | + |
| 36 | + # Constant objective |
| 37 | + ExaModels.objective(model, Min, 1.0) |
| 38 | + |
| 39 | + # Collocation model |
| 40 | + ExaModels.constraint( |
| 41 | + model, |
| 42 | + [i=1:nh, j=1:nc, s=1:nd], |
| 43 | + uc[i, j, s] == v[i,s] + h*sum(w[i,k]*(rho[j]^k/factorial(k)) for k in 1:nc), |
| 44 | + ) |
| 45 | + ExaModels.constraint( |
| 46 | + model, |
| 47 | + [i=1:nh, j=1:nc, s=1:nd], |
| 48 | + Duc[i, j, s] == sum(v[i,k]*((rho[j]*h)^(k-s)/factorial(k-s)) for k in s:nd) + |
| 49 | + h^(nd-s+1) * sum(w[i, k]*(rho[j]^(k+nd-s)/factorial(k+nd-s)) for k in 1:nc) |
| 50 | + ) |
| 51 | + # Boundary |
| 52 | + ExaModels.constraint(model, bc_1, v[1, 1] == bc[1, 1]) |
| 53 | + ExaModels.constraint(model, bc_2, v[1, 2] == bc[2, 1]) |
| 54 | + ExaModels.constraint( |
| 55 | + model, |
| 56 | + bc_3, |
| 57 | + sum(v[nh, k]*(h^(k-1)/factorial(k-1)) for k in 1:nd) + |
| 58 | + h^nd * sum(w[nh, k]/factorial(k+nd-1) for k in 1:nc) == bc[1, 2] |
| 59 | + ) |
| 60 | + ExaModels.constraint( |
| 61 | + model, |
| 62 | + bc_4, |
| 63 | + sum(v[nh, k]*(h^(k-2)/factorial(k-2)) for k in 2:nd) + |
| 64 | + h^(nd-1) * sum(w[nh, k]/factorial(k+nd-2) for k in 1:nc) == bc[2, 2] |
| 65 | + ) |
| 66 | + ExaModels.constraint( |
| 67 | + model, |
| 68 | + continuity[i=1:nh-1, s=1:nd], |
| 69 | + sum(v[i, k]*(h^(k-s)/factorial(k-s)) for k in s:nd) |
| 70 | + + h^(nd-s+1)* sum(w[i, k]/factorial(k+nd-s) for k in 1:nc) == v[i+1, s] |
| 71 | + ) |
| 72 | + ExaModels.constraint( |
| 73 | + model, |
| 74 | + collocation[i=1:nh, j=1:nc], |
| 75 | + sum(w[i, k] * (rho[j]^(k-1)/factorial(k-1)) for k in 1:nc) == |
| 76 | + R * (Duc[i, j, 2] * Duc[i, j, 3] - Duc[i, j, 1] * Duc[i, j, 4]) |
| 77 | + ) |
| 78 | + |
| 79 | + return ExaModels.ExaModel(core; kwargs...) |
| 80 | +end |
| 81 | + |
0 commit comments