human: Given a node-centered hypergraph: <hypergraph>, where nodes represent papers and hyperedges represent sets of papers co-cited by a source paper.

Details of the hypergraph:
Center node: "a numerical study of fluids with pressure dependent viscosity flowing through a rigid porous medium"
  Abstract: In this paper we consider modifications to Darcy's equation wherein the drag coefficient is a function of pressure, which is a realistic model for technological applications like enhanced oil recovery and geological carbon sequestration. We first outline the approximations behind Darcy's equation and the modifications that we propose to Darcy's equation, and derive the governing equations through a systematic approach using mixture theory. We then propose a stabilized mixed finite element formulation for the modified Darcy's equation. To solve the resulting nonlinear equations we present a solution procedure based on the consistent Newton-Raphson method. We solve representative test problems to illustrate the performance of the proposed stabilized formulation. One of the objectives of this paper is also to show that the dependence of viscosity on the pressure can have a significant effect both on the qualitative and quantitative nature of the solution.

Connected through hyperedge HE-1 (induced by source paper "a scalable variational inequality approach for flow through porous media models with pressure dependent viscosity"):
  with members:
    - "a performance spectrum for parallel computational frameworks that solve pdes"
    - "firedrake automating the finite element method by composing abstractions"
    - "large scale optimization based non negative computational framework for diffusion equations parallel implementation and performance studies"
    - "an algorithm for the optimization of finite element integration loops"
    - "variational inequality approach to enforcing the non negative constraint for advection diffusion equations"
    - "cross loop optimization of arithmetic intensity for finite element local assembly"
    - "on mesh restrictions to satisfy comparison principles maximum principles and the non negative constraint recent developments and new results"
    - "a numerical framework for diffusion controlled bimolecular reactive systems to enforce maximum principles and the non negative constraint"

Connected through hyperedge HE-2 (induced by source paper "modeling flow in porous media with double porosity permeability a stabilized mixed formulation error analysis and numerical solutions"):
  with members:
    - "mechanics based solution verification for porous media models"
    - "enforcing the non negativity constraint and maximum principles for diffusion with decay on general computational grids"
    - "dolfin automated finite element computing"
    - "on the stability of bubble functions and a stabilized mixed finite element formulation for the stokes problem"

Connected through hyperedge HE-3 (induced by source paper "a global sensitivity analysis and reduced order models for hydraulically fractured horizontal wells"):
  with members:
    - "a stabilized mixed discontinuous galerkin formulation for double porosity permeability model"
    - "a scalable variational inequality approach for flow through porous media models with pressure dependent viscosity"
    - "modeling flow in porous media with double porosity permeability a stabilized mixed formulation error analysis and numerical solutions"

Connected through hyperedge HE-4 (induced by source paper "mechanics based solution verification for porous media models"):
  with members:
    - "a numerical methodology for enforcing maximum principles and the non negative constraint for transient diffusion equations"
    - "a stabilized mixed formulation for unsteady brinkman equation based on the method of horizontal lines"
    - "discussions on driven cavity flow"

Connected through hyperedge HE-5 (induced by source paper "a mixed formulation for a modification to darcy equation based on picard linearization and numerical solutions to large scale realistic problems"):
  with members:
    - "on the stability of bubble functions and a stabilized mixed finite element formulation for the stokes problem"

Connected through hyperedge HE-6 (induced by source paper "a mixed formulation for a modification to darcy equation with applications to enhanced oil recovery and carbon dioxide sequestration"):
  with members:
    - "on the stability of bubble functions and a stabilized mixed finite element formulation for the stokes problem"

Question: Please tell me which class the center node belongs to. The 40 classes are: cs.NA(Numerical Analysis), cs.MM(Multimedia), cs.LO(Logic in Computer Science), cs.CY(Computers and Society), cs.CR(Cryptography and Security), cs.DC(Distributed, Parallel, and Cluster Computing), cs.HC(Human-Computer Interaction), cs.CE(Computational Engineering, Finance, and Science), cs.NI(Networking and Internet Architecture), cs.CC(Computational Complexity), cs.AI(Artificial Intelligence), cs.MA(Multiagent Systems), cs.GL(General Literature), cs.NE(Neural and Evolutionary Computing), cs.SC(Symbolic Computation), cs.AR(Hardware Architecture), cs.CV(Computer Vision and Pattern Recognition), cs.GR(Graphics), cs.ET(Emerging Technologies), cs.SY(Systems and Control), cs.CG(Computational Geometry), cs.OH(Other Computer Science), cs.PL(Programming Languages), cs.SE(Software Engineering), cs.LG(Machine Learning), cs.SD(Sound), cs.SI(Social and Information Networks), cs.RO(Robotics), cs.IT(Information Theory), cs.PF(Performance), cs.CL(Computation and Language), cs.IR(Information Retrieval), cs.MS(Mathematical Software), cs.FL(Formal Languages and Automata Theory), cs.DS(Data Structures and Algorithms), cs.OS(Operating Systems), cs.GT(Computer Science and Game Theory), cs.DB(Databases), cs.DL(Digital Libraries), cs.DM(Discrete Mathematics). Directly output the class name.

gpt: cs.NA(Numerical Analysis)