# Fluid-Structure Interaction Time Domain Convergence Problem

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July 21, 2022, 12:22
Fluid-Structure Interaction Time Domain Convergence Problem
#1
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Currently im trying to solve 2D Fluid-Structure Interaction on a water tank using time domain analysis with Predictor-Corrector Method developed by Liu and Sakai (2002).

I was able to simulate vertical displacement of Fluid domain that governs by Laplace equation and Boundary Element Method, but struggling on find a convergence value of 𝜕𝜑╱𝜕𝑡 on Structure Domain that will be further used for a pressure input (external force) on Finite Element Analysis of Dynamics Structure Equation. ({xdd} [M] + {x} [K] = {F} )

At the beginning of time step, the value of 𝜕𝜑╱𝜕𝑡 is stable and converged. but somehow the value of 𝜕𝜑╱𝜕𝑡 will be NaN because of there is no inflection point.

Does my formulation to find 𝜕𝜑╱𝜕𝑡 value on structure Domain is correct using modified of motion equation on Step 4 or my Predictor Corrector scheme is wrong? (.docx attachment)

I've been debugging for over 1 month and still cant solve and my scholarship is running out, I'm very appreciate for those who wants to help me any little help will be very important for me.
Attached Files
 2022-07-21 Time-Domain Fluid-Structure Interaction.docx (66.5 KB, 1 views)

July 21, 2022, 12:32
#2
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Here's my example of 𝜕𝜑╱𝜕t convergence problems. (Attachment .jpg)
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 Dphi.jpg (19.4 KB, 6 views)

 Tags bernoulli, floating structure, fsi coupling, laplace