### A Comprehensive Program for Computational Fluid Dynamics Simulations

ADINA CFD provides state-of-the-art capabilities for modeling incompressible and compressible flows. ADINA CFD is capable of modeling a wide array of fluid flows, including those in the laminar and turbulent regimes, thin-film Reynolds flow with smooth or rough boundaries, two-phase flow, non-isothermal flow and conjugate heat transfer, porous-media flow, flows with mass transfer, low- and high-speed compressible conditions, and comes equipped with material models for handling non-Newtonian fluids and real gases. General flow conditions in arbitrary geometries can be solved.

ADINA CFD may be used as a standalone program for CFD-only analyses, or it may be used in conjunction with other modules in the ADINA product suite for multiphysics applications, such as fluid-structure interaction or fluid-electromagnetic coupling analyses.

### An Advanced Software Package for Fluid Flow Applications

**Laminar & Turbulence Modelling**

ADINA CFD has the capability of modeling fluids in all flow regimes, including creeping flow or diffusive problems, and turbulent incompressible or fully compressible flows. The standard and RNG k-e turbulence models, Spalart-Allmaras turbulence model, and k-ε/SST turbulence model are available.

**Incompressible & Compressible Flow**

ADINA CFD solves the full Navier-Stokes equations or the Reynolds equations for incompressible or compressible flows. Compressible flows may be slightly compressible, such as fluid contained in an enclosure, low speed compressible, where temperature coupling must be included, or high-speed compressible as with fluids experiencing a shock wave. Combining high-speed compressible flow and the capabilities of Steered Adaptive Meshing (SAM) is particularly useful for resolving shock wave propagation. Thin-film Reynolds fluid elements can be directly connected to Navier-Stokes general fluid elements to model, for example, oil reservoirs in thin-film lubrication bearings.

**Two-phase flow & Volume of Fluid**

ADINA CFD supports the modeling of two-phase flow by utilizing the Volume of Fluid (VOF) feature. Immiscible or partially miscible fluids may be modeled using the surface-capturing method of the VOF interface. Cavitation can also be simulated using the VOF feature and coupled to FSI or used with turbulent flow.

**Conjugate Heat Transfer & Non-Isothermal Flow**

ADINA CFD has the capability to model heat transfer between solids and fluids and non-isothermal flow within a single program module. In conjugate heat transfer applications, the solid domain is modeled within ADINA CFD using fluid-solid elements. Here, the energy equation is solved entirely in the CFD model. In non-isothermal flow applications, particularly in situations where temperature loads induce compressibility effects, temperature is fully coupled to fluid flow. ADINA CFD allows for the investigation of various mechanisms of heat transfer – conduction, convection, and radiation – as they are coupled to fluid dynamics.

**Rotating Geometries – Sliding Mesh**

For models in which rotating geometries are the defining feature, such as in turbomachinery problems or stirred tanks, for example, ADINA utilizes the sliding mesh boundary condition, which permits a user to define portions of the mesh as moving relative to each other. All physical variables across the sliding mesh interface are continuous and satisfy the conservation laws. Meshes along the sliding interface may have differing subdivisions. This feature is particularly useful in Fluid-Structure Interaction problems involving one or more moving parts, but is fully applicable to fluid-only applications.

**Material Models**

ADINA has several material options describing compressible and incompressible fluids. For incompressible fluids, constant, temperature-dependent, or time-dependent viscosity, heat capacity, and thermal conductivity may be assigned to a fluid. For compressible flows, temperature-, pressure-, or temperature-pressure dependent models for viscosity, heat capacity, and thermal conductivity can be used. Flows with high Mach numbers can also be simulated using the high-speed compressible flow model definitions. Non-Newtonian fluids can be described using the Power Law, temperature-dependent Power Law, and Carreau models. Additionally, ASME Steam and porous material models are available. At temperatures and pressures for which the ideal gas law is no longer valid, ADINA supports several state equations for modeling real gas behavior, including Standard Redlich-Kwong, Aungier-Redlich-Kwong, Soave-Redlich-Kwong, and Peng-Robinson. Users may also define their own materials, by use of user-coded subroutines written in Fortran.

Surface temperature in a conjugate heat transfer analysis

of an exhaust gas manifold

Fluid-Structure Interaction simulation of a two-dimensional gear pump

### Cutting-Edge Meshing Capabilities for CFD Simulations

**Meshing**

Meshing is often viewed as an arduous, time-consuming step in the CFD modeling process. With ADINA’s advanced meshing algorithms, users can create free-form or rule-based structured meshes on arbitrarily shaped domains with ease. Meshing tools within the AUI also allow for the creation of structured boundary layer meshes, 3D swept and revolved meshes, curvature-based meshing, and automatic mesh grading.

In computations of fluid flow with structural interactions (FSI, or Fluid-Structure Interaction) or fluid flows with moving boundaries, it is necessary to update the mesh topology when the mesh is no longer valid due to distorted elements as a result of node movement. With the Steered Adaptive Meshing (SAM) feature in ADINA, mesh adaptation-repair procedures based on the Delaunay meshing methodology are accomplished which repair invalid elements by local remeshing. SAM may also be used to refine the mesh locally based on variable gradients, for example in areas of the domain that have steep gradients in velocity or temperature, thus offering an efficient and accurate mesh based on the simulated physics.

### State-of-the-Art Computational Fluid Dynamics Element Schemes

**FCBI & FCBI-C Element Schemes**

ADINA CFD offers advanced computational fluid dynamics schemes for modeling all fluid flows by use of the FCBI and FCBI-C element types. Using the FCBI, or vertex-centered, element, all coupled solution variables are solved directly in a single matrix equation. This scheme is highly stable for low Reynolds number flows, low Mach number compressible flows, and for highly nonlinear FSI problems. With FCBI-C, or cell-centered, element, solution variables are solved iteratively and stored at the cell center. FCBI-C elements are suitable for large problems (e.g., greater than 1 million DOF), as the segregated solver approach is less memory intensive, and are particularly accurate for high Reynolds number turbulent flows. The FCBI-C element is also well-suited for use with Distributed Memory Processing (DMP), making it possible to solve very large problems quickly with parallel processing.

Thermal-Fluid-Structural Analysis of a Shell and Tube Heat Exchanger

### An Integrated Program Module for Multiphysics Applications

Multiphysics problems are characterized by the interaction and dependency of two or more distinct physical fields (e.g., structural deformation, fluid flow, electric field, temperature, pore-pressure). One example is the study of cardiovascular mechanics, a Fluid-Structure Interaction problem, in which tissues comprising human arteries undergo highly nonlinear motions due to momentum exchange with pulsatile blood flow.

The ADINA Multiphysics package contains a comprehensive array of multiphysics capabilities tightly integrated in one program. Those coupled to fluid analysis include Fluid-Structure Interaction, Fluid-Electromagnetic Coupling, Fluid-Mass Transfer Coupling, and Thermal-Fluid-Structural Coupling.

In Fluid-Structure Interaction problems, fluids are fully coupled to general structures that can undergo highly nonlinear response due to large deformations, material nonlinearities, contact, and temperature-dependency. FSI analyses are a wide-reaching class of problems, and can be found in the automotive, biomechanics, turbomachinery, and nuclear power industries, among others.

In Thermal-Fluid-Structural coupling, the energy equation is solved separately in the fluid and solid domains, and the domains are coupled together by enforcing the same temperature and heat flux at the fluid-structure interface. A chief advantage of this method, is that heat generation in the solid model (i.e., due to frictional heating, plastic deformation, or viscous effects) affects the temperature field of the fluid model.

In Fluid-Mass Transfer coupling, the fluid flow is coupled to species transport, thus the species concentration affects the fluid flow profile, and vice versa. The coupling is due to the dependence of the mixture’s density and viscosity on the solute concentration. Transfer of the solute due to the flow changes the spatial distribution of the mixture density and also its viscosity, consequently affecting the flow pattern, which in turn affects the movement of the solute.

In problems concerning the coupling of fluids to electromagnetic phenomena, ADINA solves the general Maxwell’s equations coupled to fluid flow characterized by the Navier-Stokes equations. In this class of multiphysics problems, the fluid flow is driven by the Lorentz forces caused by the electromagnetic field. A common example of this coupled behavior is in microwave heating of food products.