**Case Studies**** > Fluid**

## Case List

__Case 1: Cylindrical Vessel with Fluid-Thermal Interaction__

Case 2: 2D Fluid-Structure Interaction

Case 3: Fluid Flow in U-Shaped Vessel

Case 4: 2D Fluid Flow

Case 5: 2D Fluid Mix

Case 2: 2D Fluid-Structure Interaction

Case 3: Fluid Flow in U-Shaped Vessel

Case 4: 2D Fluid Flow

Case 5: 2D Fluid Mix

## Case 1: Cylindrical Vessel with Fluid-Thermal Interaction

Water flows through a cylindrical vessel and is heated by the heaters with contact temperature. The two heaters are represented by two "temperature" surfaces to simplify the whole model. Because of symmetry, only one quarter of the model is simulated. The inlet surface has a normal velocity with a value of 5[mm/s] defined in "Laminar Flow" physics type and has a initial temperature with a value of 20[degC] defined in "Heat Transfer in Fluids" physics type. "Temperature coupling" and "Flow coupling" are set up in "Multiphysics" analysis.

## Case 2: 2D Fluid-Structure Interaction

This problem involves a fluid-structure interaction where the beam affects the flow path and the flow affects the beam deformation. The inlet is on the left having a normal inflow velocity, and the outlet is on the right having a zero pressure and a definition of "suppress backflow". The "Time-dependent" solver with times (0 range(1.005,5e-3,2)) is used to obtain the solution, in which the "Constant (Newton)" nonlinear method is applied.

## Case 3: Fluid Flow in U-Shaped Vessel

Water flowing through a U-shaped vessel is simulated. Laminar flow physics type is defined for this engineering problem. The outer surface of U-shaped vessel is defined as "No slip" wall. One side is defined as the inlet with a normal inflow velocity, 1[m/s], and the other side is defined as the outlet with a pressure, 10 [Pa], and a setting of suppress backflow. The model is meshed using tetrahedral elements with "fine" mesh size. The "Time-dependent" solver with a range of (0,0.025,2) is used to obtain the solution, in which the "Constant (Newton)" nonlinear method is applied.

**Case 4: 2D Fluid Flow**

The model is to simulate 2D laminar flow using COMSOL Multiphysics. The upper and bottom lines are defined as no-slip walls, and the boundary of three ellipses are defined as slip walls. The inlet is on the left having a normal inflow velocity, and the outlet is on the right having a pressure 10 psi and a definition of "suppress backflow". The "Time-dependent" solver with ranges of (0,0.2,3) and (3.1,0.05,6) is used to obtain the solution, in which the "Constant (Newton)" nonlinear method is applied. Partials tracing mass are defined and released at t=3.6s.

## Case 5: 2D Fluid Mix

The model is to simulate 2D laminar flow mix. There are two inlets defined with different normal inflow velocities and one outlet on the bottom with a pressure of 5 [Pa] and an options of suppress flow. The wall is defined with "no slip" boundary condition. The "Time-dependent" solver with ranges of (0,0.02,4) is used to obtain the solution, in which the "Constant (Newton)" nonlinear method is applied.

## Case 6: 3D Fluid Split and Mix

This example models a 3D split and combine mixer channel. A tracer fluid is introduced and mixed by multi-lamination. Two physics types are simulated: "Laninar flow" and "Transport of Diluted Species", which are studies in two "Stationary" steps. Two inlets have a normal inflow velocity of 1[mm/s] and one outlet has a zero pressure. One inflow has zero concentration and the other has a concentration of 1 mol/m^3.