TY - JOUR
T1 - A Priori Error Estimates for Semidiscrete Finite Element Approximations to Equations of Motion Arising in Oldroyd Fluids of Order One
AU - Goswami , D.
AU - Pani , A. K.
JO - International Journal of Numerical Analysis and Modeling
VL - 2
SP - 324
EP - 352
PY - 2011
DA - 2011/08
SN - 8
DO - http://doi.org/
UR - https://global-sci.org/intro/article_detail/ijnam/688.html
KW - Viscoelastic fluids, Oldroyd fluid of order one, uniform a priori bound in Dirichlet norm, uniform in time and optimal error estimates, nonsmooth initial data.
AB - <p style="text-align: justify;">In this paper, a semidiscrete finite element Galerkin method for
the equations of motion arising in the 2D Oldroyd model of viscoelastic fluids
of order one with the forcing term independent of time or in $L^\infty$ in time, is
analyzed. A step-by-step proof of the estimate in the Dirichlet norm for the
velocity term which is uniform in time is derived for the nonsmooth initial
data. Further, new regularity results are obtained which reflect the behavior
of solutions as $t \rightarrow 0$ and $t \rightarrow \infty$. Optimal $L^\infty(L^2)$ error estimates for the
velocity which is of order $O(t^{-\frac{1}{2}}h^2)$ and for the pressure term which is of order
$O(t^{-\frac{1}{2}}h)$ are proved for the spatial discretization using conforming elements,
when the initial data is divergence free and in $H^1_0$ . Moreover, compared to
the results available in the literature even for the Navier-Stokes equations, the
singular behavior of the pressure estimate as $t \rightarrow 0$, is improved by an order
$\frac{1}{2}$, from $t^{-1}$ to $t^{-\frac{1}{2}}$, when conforming elements are used. Finally, under the
uniqueness condition, error estimates are shown to be uniform in time.</p>