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Sequential Methods for Coupled Geomechanics and Multiphase Flow

Sequential Methods for Coupled Geomechanics and Multiphase Flow

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4.1 The distribution of the error amplification factors of the drained (top) <strong>and</strong><br />

undrained (bottom) splits with respect to pressure diffusivity χ <strong>and</strong> fre-<br />

quency. The coupling strength τ is 0.05. . . . . . . . . . . . . . . . . . . . . 97<br />

4.2 The difference of the magnitude of the error amplification factors between<br />

the drained <strong>and</strong> undrained splits. . . . . . . . . . . . . . . . . . . . . . . . . 98<br />

4.3 Case 4.1: the Terzaghi problem in one dimension (left). Case 4.2: the con-<br />

solidation problem in two dimensions (right). . . . . . . . . . . . . . . . . . 99<br />

4.4 Convergence analysis of Case 4.1: pressure (top) <strong>and</strong> displacement (bottom).<br />

The coupling strength τ = b 2 M/Kdr, is 0.95. FC, Dr, <strong>and</strong> Und indicate<br />

the fully coupled, drained split, <strong>and</strong> undrained split methods, respectively.<br />

∆td = 4cv∆t/(Lz) 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100<br />

4.5 Non-convergence of the drained split with one iteration <strong>for</strong> Case 4.1: pressure<br />

(top) <strong>and</strong> displacement (bottom). . . . . . . . . . . . . . . . . . . . . . . . . 101<br />

4.6 Convergence of the undrained split with one iteration <strong>for</strong> Case 4.1: pressure<br />

(top) <strong>and</strong> displacement (bottom). . . . . . . . . . . . . . . . . . . . . . . . . 102<br />

4.7 Comparison between more iterations <strong>and</strong> refined time step size in the drained<br />

split <strong>for</strong> Case 4.1: pressure (top) <strong>and</strong> displacement (bottom). The coupling<br />

strength is close to one (τ = 0.95). . . . . . . . . . . . . . . . . . . . . . . . 103<br />

4.8 Convergence analysis of pressure (top) <strong>and</strong> displacement (bottom) <strong>for</strong> a<br />

nearly incompressible fluid, where τ = 9.5 × 10 4 <strong>and</strong> cf = 3.5 × 10 −13 Pa −1 .<br />

The staggered method is used. The undrained split is not convergent, show-<br />

ing almost zeroth-order accuracy. The fully coupled method shows first-order<br />

accuracy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105<br />

4.9 Spatial distributions of pressure (top) <strong>and</strong> displacement (bottom) <strong>for</strong> a nearly<br />

incompressible fluid. The undrained split produces large errors, not converg-<br />

ing to the true solutions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106<br />

xx

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