Cahn-Hilliard-Hele-ShawSecond-order linear schemeUniquely solvableUnconditionally stable in energyError estimatesCoarsening dynamicsCONVEX SPLITTING SCHEMESFINITE-ELEMENT-METHODFOURIER-SPECTRAL METHODSNONLINEAR TUMOR-GROWTHVARIABLE-MOBILITYALLEN-CAHNMODELEQUATIONCONVERGENCETIME