Viscoelastic Cahn–Hilliard models for tumor growth Garcke, Harald Kovács, Balázs Trautwein, Dennis Applied Mathematics Modeling and Simulation <jats:p> We introduce a new phase field model for tumor growth where viscoelastic effects are taken into account. The model is derived from basic thermodynamical principles and consists of a convected Cahn–Hilliard equation with source terms for the tumor cells and a convected reaction–diffusion equation with boundary supply for the nutrient. Chemotactic terms, which are essential for the invasive behavior of tumors, are taken into account. The model is completed by a viscoelastic system consisting of the Navier–Stokes equation for the hydrodynamic quantities, and a general constitutive equation with stress relaxation for the left Cauchy–Green tensor associated with the elastic part of the total mechanical response of the viscoelastic material. For a specific choice of the elastic energy density and with an additional dissipative term accounting for stress diffusion, we prove existence of global-in-time weak solutions of the viscoelastic model for tumor growth in two space dimensions [Formula: see text] by the passage to the limit in a fully-discrete finite element scheme where a CFL condition, i.e. [Formula: see text], is required. </jats:p><jats:p> Moreover, in arbitrary dimensions [Formula: see text], we show stability and existence of solutions for the fully-discrete finite element scheme, where positive definiteness of the discrete Cauchy–Green tensor is proved with a regularization technique that was first introduced by Barrett and Boyaval [Existence and approximation of a (regularized) Oldroyd-B model, Math. Models Methods Appl. Sci. 21 (2011) 1783–1837]. After that, we improve the regularity results in arbitrary dimensions [Formula: see text] and in two dimensions [Formula: see text], where a CFL condition is required. Then, in two dimensions [Formula: see text], we pass to the limit in the discretization parameters and show that subsequences of discrete solutions converge to a global-in-time weak solution. Finally, we present numerical results in two dimensions [Formula: see text]. </jats:p> World Scientific Pub Co Pte Ltd 2022 info:eu-repo/semantics/article doc-type:article text http://purl.org/coar/resource_type/c_6501 https://ris.uni-paderborn.de/record/45970 Garcke H, Kovács B, Trautwein D. Viscoelastic Cahn–Hilliard models for tumor growth. <i>Mathematical Models and Methods in Applied Sciences</i>. 2022;32(13):2673-2758. doi:<a href="https://doi.org/10.1142/s0218202522500634">10.1142/s0218202522500634</a> eng info:eu-repo/semantics/altIdentifier/doi/10.1142/s0218202522500634 info:eu-repo/semantics/altIdentifier/issn/0218-2025 info:eu-repo/semantics/altIdentifier/issn/1793-6314 info:eu-repo/semantics/closedAccess