Introduction

This example analyzes an electronics component enclosure to determine the effectiveness of heat dissipation of the CPU chip's heat sink out of the enclosure by the air flow created by the cooling fan.

Increased processing power of computer chips requires designs that cool the chip effectively during operations. Heat sink geometry, fin spacing, material composition, and more are typical design variables that can improve cooling.

This page discusses:

Problem Description

This example models the heat generated by a CPU chip attached to a heat sink on a printed circuit board. The board is enclosed by a case and cooled by a fan. The case is 200 mm x 100 mm x 40 mm and is modeled as a thin surface. The fan blows air into the case through an inlet, and the air exits the case from five small vents on each side of the enclosure.

The air is assumed to have a thermal conductivity of 0.025 W/mK, a specific heat of 1005 J/Kkg, a density of 1.25 kg/m3, and a viscosity of 1.8e-5 Ns/m2. The aluminum heat sink consists of 21 uniformly spaced fins with an aspect ratio X/L (X = spacing between the fins, L = height of each fin) = 1/11. The aluminum has isotropic material properties—a thermal conductivity of 237 W/mK and a specific heat of 910 J/Kkg. The heat source is a 50-mm x 50-mm x 5-mm silicon CPU chip. The chip has isotropic material properties—a thermal conductivity of 149 W/mK and a specific heat of 710 J/Kkg.

Inlet

Outlets

Chip

Heat Sink

Workflow

The workflow diagram below provides an overview of the example. The diagram shows the apps that you use as you perform the steps in sequence. Clicking a number in the diagram opens its corresponding step in the example.

Create the simulation by first importing the model and material definitions into the 3DEXPERIENCE platform and then opening the model in the appropriate app.Use the fluid domain to define the volume in the model where the fluid is contained.Create a fluid section and two solid sections, and assign the corresponding materials.Use a finite element model (FEM) representation of your geometry to perform the simulation.Define the physics for the fluid and solid, and use a static step to determine the nature and sequence of events in a simulation scenario.Specify a contact interaction to define the thermal contact between the heat sink and the chip. Specify the chip as a volumetric heat source.Apply a velocity inlet and pressure outlet to define the directions for the fluid flow in the model.Perform a simulation to solve for the effectiveness of the heat dissipation.Display simulation data for the temperature distribution on the chip, heat sink, and air flow pattern using velocity vector plots and streamlines.
Task Description
1 Create the Fluid Simulation Create the simulation by first importing the model and material definitions into the 3DEXPERIENCE platform and then opening the model in the appropriate app.
2 Create the Fluid Domain Use the fluid domain to define the volume in the model where the fluid is contained.
3 Assign Materials Create a fluid section and two solid sections, and assign the corresponding materials.
4 Mesh the Model Use a finite element model (FEM) representation of your geometry to perform the simulation.
5 Define the Physics Define the physics for the fluid and solid, and use a static step to determine the nature and sequence of events in a simulation scenario.
6 Apply Thermal Conditions Specify a contact interaction to define the thermal contact between the heat sink and the chip. Specify the chip as a volumetric heat source.
7 Apply Inlet/Outlet Flow Conditions Apply a velocity inlet and pressure outlet to define the directions for the fluid flow in the model.
8 Solve the Simulation Perform a simulation to solve for the effectiveness of the heat dissipation.
9 Review the Results Display simulation data for the temperature distribution on the chip, heat sink, and air flow pattern using velocity vector plots and streamlines.

Complete the workflow steps in the order in which they are listed. Deviation from the instructions associated with each step might cause model or scenario errors, which might prevent convergence of the simulation.